diff --git a/NEWS b/NEWS
index 1a902c05a6..00849e701f 100644
--- a/NEWS
+++ b/NEWS
@@ -55,6 +55,20 @@ New Functionality
   for which no connection state information is available in the core anymore. These
   cases will raise the new ``expired_conn_weird`` event.
 
+- Broker Store table synchronization (Experimental).
+
+  Zeek now supports synchronizing tables/sets across clusters using a backing broker
+  store. The same feature also allows persistent storage of data in tables/sets
+  over Zeek restarts. This feature is implemented using the new ```&backend``` attribute.
+
+  To synchronize a table over a cluster, you can e.g. use:
+
+  ```global t: table[string] of count &backend=Broker::MEMORY;```
+
+  This feature is documented in detail here: FIXME.
+
+	Note: this feature is experimental and the syntax/featureset can change in the future.
+
 Changed Functionality
 ---------------------
 
diff --git a/scripts/base/frameworks/broker/store.zeek b/scripts/base/frameworks/broker/store.zeek
index 2456ccbf2f..8a9019bb40 100644
--- a/scripts/base/frameworks/broker/store.zeek
+++ b/scripts/base/frameworks/broker/store.zeek
@@ -25,8 +25,14 @@ export {
 	## A negative/zero value indicates to never buffer commands.
 	const default_clone_mutation_buffer_interval = 2min &redef;
 
+	## If set to true, the current node is the master node for broker stores
+	## backing zeek tables. By default this value will be automatically set to
+	## true in standalone mode, or on the manager node of a cluster. This value
+	## should not typically be changed manually.
 	const auto_store_master = T &redef;
 
+	## The directory used for storing persistent database files when using brokerstore
+	## backed zeek tables.
 	const auto_store_db_directory = "." &redef;
 
 	## Whether a data store query could be completed or not.
diff --git a/scripts/base/frameworks/cluster/broker-stores.zeek b/scripts/base/frameworks/cluster/broker-stores.zeek
index 112b53db58..1513e6776d 100644
--- a/scripts/base/frameworks/cluster/broker-stores.zeek
+++ b/scripts/base/frameworks/cluster/broker-stores.zeek
@@ -1,11 +1,23 @@
+##! This script deals with the cluster parts of broker backed zeek tables.
+##! It makes sure that the master store is set correctly and that clones
+##! are automatically created on the non-manager nodes.
+
+# Note - this script should become unnecessary in the future, when we just can
+# speculatively attach clones. This should be possible once the new ALM broker
+# transport becomes available.
+
 @load ./main
 
 module Broker;
 
 export {
+	## Event that is used by the manager to announce the master stores for zeek backed
+	## tables that is uses.
 	global announce_masters: event(masters: set[string]);
 }
 
+# If we are not the manager - disable automatically generating masters. We will attach
+# clones instead.
 @if ( Cluster::is_enabled() && Cluster::local_node_type() != Cluster::MANAGER )
 redef Broker::auto_store_master = F;
 @endif
@@ -24,6 +36,7 @@ event zeek_init()
 		}
 	}
 
+# Send the auto masters we created to the newly connected node
 event Broker::peer_added(endpoint: Broker::EndpointInfo, msg: string) &priority=1
 	{
 	if ( ! Cluster::is_enabled() )
@@ -39,6 +52,7 @@ event Broker::announce_masters(masters: set[string])
 	{
 	for ( i in masters )
 		{
+		# this magic name for the store is created in broker/Manager.cc for the manager.
 		local name = "___sync_store_" + i;
 		Broker::create_clone(name);
 		}
diff --git a/scripts/base/init-bare.zeek b/scripts/base/init-bare.zeek
index 6036a0bc66..aa8c28bd1e 100644
--- a/scripts/base/init-bare.zeek
+++ b/scripts/base/init-bare.zeek
@@ -734,7 +734,7 @@ type script_id: record {
 	enum_constant: bool;	##< True if the identifier is an enum value.
 	option_value: bool;	##< True if the identifier is an option.
 	redefinable: bool;	##< True if the identifier is declared with the :zeek:attr:`&redef` attribute.
-	broker_backend: bool; ##< True if the identifier has a broker backend defined using the  :zeek:attr:`&backend` attribute.
+	broker_backend: bool;	##< True if the identifier has a broker backend defined using the  :zeek:attr:`&backend` attribute.
 	value: any &optional;	##< The current value of the identifier.
 };
 
diff --git a/src/Attr.cc b/src/Attr.cc
index 04905ef8d4..3aff6718dc 100644
--- a/src/Attr.cc
+++ b/src/Attr.cc
@@ -8,6 +8,7 @@
 #include "Val.h"
 #include "IntrusivePtr.h"
 #include "threading/SerialTypes.h"
+#include "input/Manager.h"
 
 namespace zeek::detail {
 
@@ -19,8 +20,8 @@ const char* attr_name(AttrTag t)
 		"&read_expire", "&write_expire", "&create_expire",
 		"&raw_output", "&priority",
 		"&group", "&log", "&error_handler", "&type_column",
-	    "(&tracked)", "&on_change", "&broker_store", "&backend",
-		"&deprecated",
+	    "(&tracked)", "&on_change", "&broker_store",
+	    "&broker_allow_complex_type", "&backend", "&deprecated",
 	};
 
 	return attr_names[int(t)];
@@ -450,6 +451,10 @@ void Attributes::CheckAttr(Attr* a)
 			{
 			Error("&broker_store and &read_expire cannot be used simultaneously");
 			}
+		if ( Find(ATTR_BACKEND) )
+			{
+			Error("&broker_store and &backend cannot be used simultaneously");
+			}
 		}
 		// fallthrough
 	case ATTR_EXPIRE_WRITE:
@@ -535,6 +540,10 @@ void Attributes::CheckAttr(Attr* a)
 			{
 			Error("&broker_store and &expire_func cannot be used simultaneously");
 			}
+		if ( Find(ATTR_BACKEND ) )
+			{
+			Error("&backend and &expire_func cannot be used simultaneously");
+			}
 		}
 		break;
 
@@ -607,7 +616,7 @@ void Attributes::CheckAttr(Attr* a)
 		{
 		if ( ! global_var || type->Tag() != TYPE_TABLE )
 			{
-			Error("&broker_store only applicable to global sets/tables");
+			Error("&backend only applicable to global sets/tables");
 			break;
 			}
 
@@ -615,7 +624,7 @@ void Attributes::CheckAttr(Attr* a)
 		// are here. We will do that later - before actually attaching to a broker store
 		if ( a->GetExpr()->GetType()->Tag() != TYPE_ENUM )
 			{
-			Error("&broker_store must take an enum argument");
+			Error("&backend must take an enum argument");
 			break;
 			}
 
@@ -625,6 +634,14 @@ void Attributes::CheckAttr(Attr* a)
 			Error("&backend only supports one-element set/table indexes");
 			}
 
+		// Only support atomic types for the moment.
+		if ( ! type->AsTableType()->IsSet() &&
+		     ! input::Manager::IsCompatibleType(type->AsTableType()->Yield().get(), true) &&
+		     ! Find(ATTR_BROKER_STORE_ALLOW_COMPLEX) )
+			{
+			Error("&backend only supports atomic types as table value");
+			}
+
 		if ( Find(ATTR_EXPIRE_FUNC ) )
 			{
 			Error("&backend and &expire_func cannot be used simultaneously");
@@ -655,11 +672,18 @@ void Attributes::CheckAttr(Attr* a)
 			}
 
 		// Temporary since Broker does not support ListVals - and we cannot easily convert to set/vector
-		if ( type->AsTableType()->GetIndexTypes().size() != 1 )
+		if ( type->AsTableType()->GetIndexTypes().size() != 1 && ! Find(ATTR_BROKER_STORE_ALLOW_COMPLEX) )
 			{
 			Error("&broker_store only supports one-element set/table indexes");
 			}
 
+		if ( ! type->AsTableType()->IsSet() &&
+		     ! input::Manager::IsCompatibleType(type->AsTableType()->Yield().get(), true) &&
+		     ! Find(ATTR_BROKER_STORE_ALLOW_COMPLEX) )
+			{
+			Error("&broker_store only supports atomic types as table value");
+			}
+
 		if ( Find(ATTR_EXPIRE_FUNC ) )
 			{
 			Error("&broker_store and &expire_func cannot be used simultaneously");
@@ -668,8 +692,21 @@ void Attributes::CheckAttr(Attr* a)
 			{
 			Error("&broker_store and &read_expire cannot be used simultaneously");
 			}
+		if ( Find(ATTR_BACKEND) )
+			{
+			Error("&backend and &broker_store cannot be used simultaneously");
+			}
 		break;
 		}
+
+	case ATTR_BROKER_STORE_ALLOW_COMPLEX:
+		{
+		if ( type->Tag() != TYPE_TABLE )
+			{
+			Error("&broker_allow_complex_type only applicable to sets/tables");
+			break;
+			}
+		}
 	case ATTR_TRACKED:
 		// FIXME: Check here for global ID?
 		break;
diff --git a/src/Attr.h b/src/Attr.h
index 9d52fa8bd2..0628530ad0 100644
--- a/src/Attr.h
+++ b/src/Attr.h
@@ -42,6 +42,7 @@ enum AttrTag {
 	ATTR_TRACKED,	// hidden attribute, tracked by NotifierRegistry
 	ATTR_ON_CHANGE, // for table change tracking
 	ATTR_BROKER_STORE, // for broker-store backed tables
+	ATTR_BROKER_STORE_ALLOW_COMPLEX, // for broker-store backed tables
 	ATTR_BACKEND, // for broker-store backed tabled
 	ATTR_DEPRECATED,
 	NUM_ATTRS // this item should always be last
diff --git a/src/Val.cc b/src/Val.cc
index 1945cdf5d7..133ecad543 100644
--- a/src/Val.cc
+++ b/src/Val.cc
@@ -1515,7 +1515,7 @@ void TableVal::SetAttrs(detail::AttributesPtr a)
 		change_func = cf->GetExpr();
 
 	auto bs = attrs->Find(zeek::detail::ATTR_BROKER_STORE);
-	if ( bs && broker_store.empty() ) // this does not mesh well with being updated several times
+	if ( bs && broker_store.empty() )
 		{
 		IntrusivePtr<Val> c = bs->GetExpr()->Eval(nullptr);
 		assert(c);
@@ -2181,8 +2181,6 @@ void TableVal::SendToStore(const Val* index, const TableEntryVal* new_entry_val,
 			index_val = index;
 			}
 
-		// FIXME: switch back to just storing tables directly in the broker store?
-		// me which store a change came from - and this still seems to be missing from the store_events. (Or I am blind).
 		auto broker_index = bro_broker::val_to_data(index_val);
 
 		if ( ! broker_index )
diff --git a/src/Val.h b/src/Val.h
index dd14abc9a1..ef02fbc3f3 100644
--- a/src/Val.h
+++ b/src/Val.h
@@ -785,7 +785,7 @@ public:
 	 * @param new_val  The value to assign at the index.  For a set, this
 	 * must be nullptr.
 	 * @param broker_forward Controls if the value will be forwarded to attached
-	 *                       broker stores.
+	 *        broker stores.
 	 * @return  True if the assignment type-checked.
 	 */
 	bool Assign(ValPtr index, ValPtr new_val, bool broker_forward = true);
@@ -799,7 +799,7 @@ public:
 	 * @param new_val  The value to assign at the index.  For a set, this
 	 * must be nullptr.
 	 * @param broker_forward Controls if the value will be forwarded to attached
-	 *                       broker stores.
+	 *        broker stores.
 	 * @return  True if the assignment type-checked.
 	 */
 	bool Assign(ValPtr index, std::unique_ptr<HashKey> k,
@@ -926,7 +926,7 @@ public:
 	 * Remove an element from the table and return it.
 	 * @param index  The index to remove.
 	 * @param broker_forward Controls if the remove operation will be forwarded to attached
-	 *                       broker stores.
+	 *        broker stores.
 	 * @return  The value associated with the index if it exists, else nullptr.
 	 * For a sets that don't really contain associated values, a placeholder
 	 * value is returned to differentiate it from non-existent index (nullptr),
@@ -1023,6 +1023,10 @@ public:
 	// on zeek::RecordTypes.
 	static void DoneParsing();
 
+	/**
+	 * Sets the name of the broker store that is backing this table.
+	 * @param store store that is backing this table.
+	 */
 	void SetBrokerStore(const std::string& store) { broker_store = store; }
 
 protected:
diff --git a/src/broker/Manager.cc b/src/broker/Manager.cc
index e9918d11a1..cc689bbf90 100644
--- a/src/broker/Manager.cc
+++ b/src/broker/Manager.cc
@@ -238,7 +238,8 @@ void Manager::InitializeBrokerStoreForwarding()
 			// we only create masters here. For clones, we do all the work of setting up
 			// the forwarding - but we do not try to initialize the clone. We can only initialize
 			// the clone, once a node has a connection to a master. This is currently done in scriptland
-			// - check FIXME.
+			// in scripts/base/frameworks/cluster/broker-stores.zeek. Once the ALM transport is ready
+			// we can change over to doing this here.
 			if ( ! zeek_table_manager )
 				continue;
 
@@ -956,7 +957,7 @@ void Manager::Process()
 
 		if ( broker::topics::store_events.prefix_of(topic) )
 			{
-			ProcessStoreEvent(topic, std::move(msg));
+			ProcessStoreEvent(std::move(msg));
 			continue;
 			}
 
@@ -995,7 +996,7 @@ void Manager::Process()
 		}
 	}
 
-void Manager::ProcessStoreEvent(const broker::topic& topic, broker::data msg)
+void Manager::ProcessStoreEvent(broker::data msg)
 	{
 	if ( auto insert = broker::store_event::insert::make(msg) )
 		{
@@ -1016,20 +1017,18 @@ void Manager::ProcessStoreEvent(const broker::topic& topic, broker::data msg)
 
 		DBG_LOG(DBG_BROKER, "Store %s: Insert: %s:%s (%s:%s)", insert.store_id().c_str(), to_string(insert.key()).c_str(), to_string(insert.value()).c_str(), insert.key().get_type_name(), insert.value().get_type_name());
 
-
 		if ( table->GetType()->IsSet() && data.get_type() != broker::data::type::none )
 			{
 			reporter->Error("ProcessStoreEvent Insert got %s when expecting set", data.get_type_name());
 			return;
 			}
 
-		// FIXME: expiry!
 		const auto& its = table->GetType()->AsTableType()->GetIndexTypes();
 		assert( its.size() == 1 );
-		auto zeek_key = data_to_val(std::move(key), its[0].get());
+		auto zeek_key = data_to_val(key, its[0].get());
 		if ( ! zeek_key )
 			{
-			reporter->Error("ProcessStoreEvent: failed to convert key");
+			reporter->Error("ProcessStoreEvent: could not convert key \"%s\" for store \"%s\" while receiving remote insert. This probably means the tables have different types on different nodes.", to_string(key).c_str(), insert.store_id().c_str());
 			return;
 			}
 
@@ -1040,10 +1039,10 @@ void Manager::ProcessStoreEvent(const broker::topic& topic, broker::data msg)
 			}
 
 		// it is a table
-		auto zeek_value = data_to_val(std::move(data), table->GetType()->Yield().get());
+		auto zeek_value = data_to_val(data, table->GetType()->Yield().get());
 		if ( ! zeek_value )
 			{
-			reporter->Error("ProcessStoreEvent: failed to convert value");
+			reporter->Error("ProcessStoreEvent: could not convert value \"%s\" for key \"%s\" in store \"%s\" while receiving remote insert. This probably means the tables have different types on different nodes.", to_string(data).c_str(), to_string(key).c_str(), insert.store_id().c_str());
 			return;
 			}
 			table->Assign(zeek_key, zeek_value, false);
@@ -1075,10 +1074,10 @@ void Manager::ProcessStoreEvent(const broker::topic& topic, broker::data msg)
 
 		const auto& its = table->GetType()->AsTableType()->GetIndexTypes();
 		assert( its.size() == 1 );
-		auto zeek_key = data_to_val(std::move(key), its[0].get());
+		auto zeek_key = data_to_val(key, its[0].get());
 		if ( ! zeek_key )
 			{
-			reporter->Error("ProcessStoreEvent: failed to convert key");
+			reporter->Error("ProcessStoreEvent: could not convert key \"%s\" for store \"%s\" while receiving remote update. This probably means the tables have different types on different nodes.", to_string(key).c_str(), insert.store_id().c_str());
 			return;
 			}
 
@@ -1089,10 +1088,10 @@ void Manager::ProcessStoreEvent(const broker::topic& topic, broker::data msg)
 			}
 
 		// it is a table
-		auto zeek_value = data_to_val(std::move(data), table->GetType()->Yield().get());
+		auto zeek_value = data_to_val(data, table->GetType()->Yield().get());
 		if ( ! zeek_value )
 			{
-			reporter->Error("ProcessStoreEvent: failed to convert value");
+			reporter->Error("ProcessStoreEvent: could not convert value \"%s\" for key \"%s\" in store \"%s\" while receiving remote update. This probably means the tables have different types on different nodes.", to_string(data).c_str(), to_string(key).c_str(), insert.store_id().c_str());
 			return;
 			}
 			table->Assign(zeek_key, zeek_value, false);
@@ -1115,17 +1114,17 @@ void Manager::ProcessStoreEvent(const broker::topic& topic, broker::data msg)
 		DBG_LOG(DBG_BROKER, "Store %s: Erase key %s", erase.store_id().c_str(), to_string(key).c_str());
 		const auto& its = table->GetType()->AsTableType()->GetIndexTypes();
 		assert( its.size() == 1 );
-		auto zeek_key = data_to_val(std::move(key), its[0].get());
+		auto zeek_key = data_to_val(key, its[0].get());
 		if ( ! zeek_key )
 			{
-			reporter->Error("ProcessStoreEvent: failed to convert key");
+			reporter->Error("ProcessStoreEvent: could not convert key \"%s\" for store \"%s\" while receiving remote erase. This probably means the tables have different types on different nodes.", to_string(key).c_str(), insert.store_id().c_str());
 			return;
 			}
 		table->Remove(*zeek_key, false);
 		}
 	else if ( auto expire = broker::store_event::expire::make(msg) )
 		{
-		// We just ignore expirys - expiring information on the Zeek side is handled by Zeek itself.
+		// We just ignore expiries - expiring information on the Zeek side is handled by Zeek itself.
 #ifdef DEBUG
 		// let's only debug log for stores that we know.
 		auto storehandle = broker_mgr->LookupStore(expire.store_id());
@@ -1685,7 +1684,7 @@ void Manager::BrokerStoreToZeekTable(const std::string& name, const StoreHandleV
 		auto zeek_key = data_to_val(key, its[0].get());
 		if ( ! zeek_key )
 			{
-			reporter->Error("Failed to convert key %s while importing broker store to table for store %s. Aborting import.", to_string(key).c_str(), name.c_str());
+			reporter->Error("Failed to convert key \"%s\" while importing broker store to table for store \"%s\". Aborting import.", to_string(key).c_str(), name.c_str());
 			// just abort - this probably means the types are incompatible
 			return;
 			}
diff --git a/src/broker/Manager.h b/src/broker/Manager.h
index 513412affe..18b6921641 100644
--- a/src/broker/Manager.h
+++ b/src/broker/Manager.h
@@ -303,6 +303,15 @@ public:
 	 */
 	StoreHandleVal* LookupStore(const std::string& name);
 
+	/**
+	 * Register a zeek table that is associated with a broker store that is backing it. This
+	 * causes all changes that happen to the brokerstore in the future to be applied to the zeek
+	 * table.
+	 * A single broker store can only be forwarded to a single table.
+	 * @param name name of the broker store
+	 * @param table pointer to the table/set that is being backed
+	 * @return true on success, false if the named store is already being forwarded.
+	 */
 	bool AddForwardedStore(const std::string& name, zeek::IntrusivePtr<zeek::TableVal> table);
 
 	/**
@@ -350,7 +359,8 @@ public:
 private:
 
 	void DispatchMessage(const broker::topic& topic, broker::data msg);
-	void ProcessStoreEvent(const broker::topic& topic, broker::data msg);
+	// Process events used for broker store backed zeek tables
+	void ProcessStoreEvent(broker::data msg);
 	void ProcessEvent(const broker::topic& topic, broker::zeek::Event ev);
 	bool ProcessLogCreate(broker::zeek::LogCreate lc);
 	bool ProcessLogWrite(broker::zeek::LogWrite lw);
@@ -359,6 +369,7 @@ private:
 	void ProcessError(broker::error err);
 	void ProcessStoreResponse(StoreHandleVal*, broker::store::response response);
 	void FlushPendingQueries();
+	// Initializes the masters for broker backed zeek tables when using the &backend attribute
 	void InitializeBrokerStoreForwarding();
 	// Check if a broker store is associated to a table on the Zeek side.
 	void CheckForwarding(const std::string& name);
diff --git a/src/parse.y b/src/parse.y
index 8257c84600..5830dd1445 100644
--- a/src/parse.y
+++ b/src/parse.y
@@ -5,7 +5,7 @@
 // Switching parser table type fixes ambiguity problems.
 %define lr.type ielr
 
-%expect 123
+%expect 129
 
 %token TOK_ADD TOK_ADD_TO TOK_ADDR TOK_ANY
 %token TOK_ATENDIF TOK_ATELSE TOK_ATIF TOK_ATIFDEF TOK_ATIFNDEF
@@ -24,7 +24,8 @@
 %token TOK_ATTR_ADD_FUNC TOK_ATTR_DEFAULT TOK_ATTR_OPTIONAL TOK_ATTR_REDEF
 %token TOK_ATTR_DEL_FUNC TOK_ATTR_EXPIRE_FUNC
 %token TOK_ATTR_EXPIRE_CREATE TOK_ATTR_EXPIRE_READ TOK_ATTR_EXPIRE_WRITE
-%token TOK_ATTR_RAW_OUTPUT TOK_ATTR_ON_CHANGE TOK_ATTR_BROKER_STORE TOK_ATTR_BACKEND
+%token TOK_ATTR_RAW_OUTPUT TOK_ATTR_ON_CHANGE TOK_ATTR_BROKER_STORE
+%token TOK_ATTR_BROKER_STORE_ALLOW_COMPLEX TOK_ATTR_BACKEND
 %token TOK_ATTR_PRIORITY TOK_ATTR_LOG TOK_ATTR_ERROR_HANDLER
 %token TOK_ATTR_TYPE_COLUMN TOK_ATTR_DEPRECATED
 
@@ -1355,7 +1356,7 @@ attr_list:
 
 attr:
 		TOK_ATTR_DEFAULT '=' expr
-		        { $$ = new zeek::detail::Attr(zeek::detail::ATTR_DEFAULT, {zeek::AdoptRef{}, $3}); }
+			{ $$ = new zeek::detail::Attr(zeek::detail::ATTR_DEFAULT, {zeek::AdoptRef{}, $3}); }
 	|	TOK_ATTR_OPTIONAL
 			{ $$ = new zeek::detail::Attr(zeek::detail::ATTR_OPTIONAL); }
 	|	TOK_ATTR_REDEF
@@ -1368,6 +1369,8 @@ attr:
 			{ $$ = new zeek::detail::Attr(zeek::detail::ATTR_ON_CHANGE, {zeek::AdoptRef{}, $3}); }
 	|	TOK_ATTR_BROKER_STORE '=' expr
 			{ $$ = new zeek::detail::Attr(zeek::detail::ATTR_BROKER_STORE, {zeek::AdoptRef{}, $3}); }
+	|	TOK_ATTR_BROKER_STORE_ALLOW_COMPLEX
+			{ $$ = new zeek::detail::Attr(zeek::detail::ATTR_BROKER_STORE_ALLOW_COMPLEX); }
 	|	TOK_ATTR_BACKEND '=' expr
 			{ $$ = new zeek::detail::Attr(zeek::detail::ATTR_BACKEND, {zeek::AdoptRef{}, $3}); }
 	|	TOK_ATTR_EXPIRE_FUNC '=' expr
diff --git a/src/scan.l b/src/scan.l
index 41228eef49..ba25c2de62 100644
--- a/src/scan.l
+++ b/src/scan.l
@@ -285,6 +285,7 @@ when	return TOK_WHEN;
 &write_expire	return TOK_ATTR_EXPIRE_WRITE;
 &on_change	return TOK_ATTR_ON_CHANGE;
 &broker_store return TOK_ATTR_BROKER_STORE;
+&broker_allow_complex_type return TOK_ATTR_BROKER_STORE_ALLOW_COMPLEX;
 &backend return TOK_ATTR_BACKEND;
 
 @deprecated.* {
diff --git a/testing/btest/Baseline/broker.store.brokerstore-backend-invalid/.stderr b/testing/btest/Baseline/broker.store.brokerstore-backend-invalid/.stderr
new file mode 100644
index 0000000000..7894cdb98f
--- /dev/null
+++ b/testing/btest/Baseline/broker.store.brokerstore-backend-invalid/.stderr
@@ -0,0 +1,5 @@
+error in /this/is/a/path/brokerstore-backend-invalid.zeek, line 12: &backend only supports one-element set/table indexes (&backend=Broker::MEMORY)
+error in /this/is/a/path/broker.store.brokerstore-backend-invalid/brokerstore-backend-invalid.zeek, line 13: &backend only supports atomic types as table value (&backend=Broker::MEMORY)
+error in /this/is/a/path/broker.store.brokerstore-backend-invalid/brokerstore-backend-invalid.zeek, line 14: &backend and &read_expire cannot be used simultaneously (&read_expire=5.0 secs, &backend=Broker::MEMORY)
+error in /this/is/a/path/broker.store.brokerstore-backend-invalid/brokerstore-backend-invalid.zeek, line 15: &backend and &broker_store cannot be used simultaneously (&broker_store=store, &backend=Broker::MEMORY)
+error in /this/is/a/path/broker.store.brokerstore-backend-invalid/brokerstore-backend-invalid.zeek, line 16: &backend only applicable to global sets/tables (&backend=Broker::MEMORY)
diff --git a/testing/btest/Baseline/broker.store.brokerstore-backend-simple-incompatible/worker-1..stderr b/testing/btest/Baseline/broker.store.brokerstore-backend-simple-incompatible/worker-1..stderr
new file mode 100644
index 0000000000..8a5d27c280
--- /dev/null
+++ b/testing/btest/Baseline/broker.store.brokerstore-backend-simple-incompatible/worker-1..stderr
@@ -0,0 +1,3 @@
+error: ProcessStoreEvent: could not convert value "b" for key "a" in store "___sync_store_TestModule::s" while receiving remote insert. This probably means the tables have different types on different nodes.
+error: ProcessStoreEvent: could not convert key "a" for store "___sync_store_TestModule::t" while receiving remote insert. This probably means the tables have different types on different nodes.
+received termination signal
diff --git a/testing/btest/Baseline/broker.store.brokerstore-backend-sqlite-incompatible/.stderr b/testing/btest/Baseline/broker.store.brokerstore-backend-sqlite-incompatible/.stderr
new file mode 100644
index 0000000000..ce13e7d1a4
--- /dev/null
+++ b/testing/btest/Baseline/broker.store.brokerstore-backend-sqlite-incompatible/.stderr
@@ -0,0 +1 @@
+error: Failed to convert key "a" while importing broker store to table for store "___sync_store_TestModule::t". Aborting import.
diff --git a/testing/btest/broker/store/brokerstore-attr-clone.zeek b/testing/btest/broker/store/brokerstore-attr-clone.zeek
index e618196f0d..429c8e6d4f 100644
--- a/testing/btest/broker/store/brokerstore-attr-clone.zeek
+++ b/testing/btest/broker/store/brokerstore-attr-clone.zeek
@@ -27,7 +27,7 @@ type testrec: record {
 
 global t: table[string] of count &broker_store="table";
 global s: set[string] &broker_store="set";
-global r: table[string] of testrec &broker_store="rec";
+global r: table[string] of testrec &broker_allow_complex_type &broker_store="rec";
 
 event zeek_init()
 	{
@@ -73,7 +73,7 @@ type testrec: record {
 
 global t: table[string] of count &broker_store="table";
 global s: set[string] &broker_store="set";
-global r: table[string] of testrec &broker_store="rec";
+global r: table[string] of testrec &broker_allow_complex_type &broker_store="rec";
 
 event zeek_init()
 	{
@@ -133,7 +133,7 @@ type testrec: record {
 
 global t: table[string] of count &broker_store="table";
 global s: set[string] &broker_store="set";
-global r: table[string] of testrec &broker_store="rec";
+global r: table[string] of testrec &broker_allow_complex_type &broker_store="rec";
 
 event zeek_init()
 	{
diff --git a/testing/btest/broker/store/brokerstore-attr-expire.zeek b/testing/btest/broker/store/brokerstore-attr-expire.zeek
index 0b12e4df96..be58d3e005 100644
--- a/testing/btest/broker/store/brokerstore-attr-expire.zeek
+++ b/testing/btest/broker/store/brokerstore-attr-expire.zeek
@@ -62,7 +62,7 @@ function print_keys()
 
 global t: table[string] of count &broker_store="table" &create_expire=4sec &on_change=change_t;
 global s: table[string] of count &broker_store="set" &write_expire=3sec &on_change=change_s;
-global r: table[string] of testrec &broker_store="rec" &write_expire=5sec &on_change=change_r;
+global r: table[string] of testrec &broker_allow_complex_type &broker_store="rec" &write_expire=5sec &on_change=change_r;
 
 event zeek_init()
 	{
@@ -154,7 +154,7 @@ function change_r(tbl: any, tpe: TableChange, idx: string, idxb: testrec)
 
 global t: table[string] of count &broker_store="table" &create_expire=4sec &on_change=change_t;
 global s: table[string] of count &broker_store="set" &write_expire=3sec &on_change=change_s;
-global r: table[string] of testrec &broker_store="rec" &write_expire=5sec &on_change=change_r;
+global r: table[string] of testrec &broker_allow_complex_type &broker_store="rec" &write_expire=5sec &on_change=change_r;
 
 event zeek_init()
 	{
diff --git a/testing/btest/broker/store/brokerstore-attr-persistence-clone.zeek b/testing/btest/broker/store/brokerstore-attr-persistence-clone.zeek
index 5f6b9ffe87..bece4f119b 100644
--- a/testing/btest/broker/store/brokerstore-attr-persistence-clone.zeek
+++ b/testing/btest/broker/store/brokerstore-attr-persistence-clone.zeek
@@ -29,7 +29,7 @@ type testrec: record {
 
 global t: table[string] of count &broker_store="table";
 global s: set[string] &broker_store="set";
-global r: table[string] of testrec &broker_store="rec";
+global r: table[string] of testrec &broker_allow_complex_type &broker_store="rec";
 
 event zeek_init()
 	{
@@ -73,7 +73,7 @@ type testrec: record {
 
 global t: table[string] of count &broker_store="table";
 global s: set[string] &broker_store="set";
-global r: table[string] of testrec &broker_store="rec";
+global r: table[string] of testrec &broker_allow_complex_type &broker_store="rec";
 
 event zeek_init()
 	{
@@ -114,7 +114,7 @@ type testrec: record {
 
 global t: table[string] of count &broker_store="table";
 global s: set[string] &broker_store="set";
-global r: table[string] of testrec &broker_store="rec";
+global r: table[string] of testrec &broker_allow_complex_type &broker_store="rec";
 
 event zeek_init()
 	{
diff --git a/testing/btest/broker/store/brokerstore-attr-persistence.zeek b/testing/btest/broker/store/brokerstore-attr-persistence.zeek
index 5004b12b91..abd40df407 100644
--- a/testing/btest/broker/store/brokerstore-attr-persistence.zeek
+++ b/testing/btest/broker/store/brokerstore-attr-persistence.zeek
@@ -24,7 +24,7 @@ type testrec: record {
 
 global t: table[string] of count &broker_store="table";
 global s: set[string] &broker_store="set";
-global r: table[string] of testrec &broker_store="rec";
+global r: table[string] of testrec &broker_allow_complex_type &broker_store="rec";
 
 event zeek_init()
 	{
@@ -66,7 +66,7 @@ type testrec: record {
 
 global t: table[string] of count &broker_store="table";
 global s: set[string] &broker_store="set";
-global r: table[string] of testrec &broker_store="rec";
+global r: table[string] of testrec &broker_allow_complex_type &broker_store="rec";
 
 event zeek_init()
 	{
diff --git a/testing/btest/broker/store/brokerstore-attr-simple.zeek b/testing/btest/broker/store/brokerstore-attr-simple.zeek
index ac2bfd2233..95ef10454f 100644
--- a/testing/btest/broker/store/brokerstore-attr-simple.zeek
+++ b/testing/btest/broker/store/brokerstore-attr-simple.zeek
@@ -23,7 +23,7 @@ type testrec: record {
 
 global t: table[string] of count &broker_store="table";
 global s: set[string] &broker_store="set";
-global r: table[string] of testrec &broker_store="rec";
+global r: table[string] of testrec &broker_allow_complex_type &broker_store="rec";
 
 event zeek_init()
 	{
@@ -83,7 +83,7 @@ type testrec: record {
 
 global t: table[string] of count &broker_store="table";
 global s: set[string] &broker_store="set";
-global r: table[string] of testrec &broker_store="rec";
+global r: table[string] of testrec &broker_allow_complex_type &broker_store="rec";
 
 event zeek_init()
 	{
diff --git a/testing/btest/broker/store/brokerstore-backend-invalid.zeek b/testing/btest/broker/store/brokerstore-backend-invalid.zeek
new file mode 100644
index 0000000000..cad1828213
--- /dev/null
+++ b/testing/btest/broker/store/brokerstore-backend-invalid.zeek
@@ -0,0 +1,16 @@
+# @TEST-EXEC-FAIL: zeek -B broker %INPUT
+# @TEST-EXEC: TEST_DIFF_CANONIFIER=$SCRIPTS/diff-remove-abspath btest-diff .stderr
+
+module TestModule;
+
+type testrec: record {
+	a: count;
+	b: string;
+	c: set[string];
+};
+
+global a: table[string, count] of count &backend=Broker::MEMORY;
+global b: table[string] of testrec &backend=Broker::MEMORY;
+global c: table[string] of count &read_expire=5sec &backend=Broker::MEMORY;
+global d: table[string] of count &broker_store="store" &backend=Broker::MEMORY;
+global f: count &backend=Broker::MEMORY;
diff --git a/testing/btest/broker/store/brokerstore-backend-simple-incompatible.zeek b/testing/btest/broker/store/brokerstore-backend-simple-incompatible.zeek
new file mode 100644
index 0000000000..ce07488da0
--- /dev/null
+++ b/testing/btest/broker/store/brokerstore-backend-simple-incompatible.zeek
@@ -0,0 +1,67 @@
+# @TEST-PORT: BROKER_PORT1
+# @TEST-PORT: BROKER_PORT2
+# @TEST-PORT: BROKER_PORT3
+
+# @TEST-EXEC: btest-bg-run manager-1 "ZEEKPATH=$ZEEKPATH:.. CLUSTER_NODE=manager-1 zeek -B broker ../master.zeek >../master.out"
+# @TEST-EXEC: btest-bg-run worker-1 "ZEEKPATH=$ZEEKPATH:.. CLUSTER_NODE=worker-1 zeek -B broker ../clone.zeek >../clone.out"
+# @TEST-EXEC: btest-bg-run worker-2 "ZEEKPATH=$ZEEKPATH:.. CLUSTER_NODE=worker-2 zeek -B broker ../clone.zeek >../clone2.out"
+# @TEST-EXEC: btest-bg-wait 15
+#
+# @TEST-EXEC: btest-diff worker-1/.stderr
+
+@TEST-START-FILE cluster-layout.zeek
+redef Cluster::nodes = {
+	["manager-1"] = [$node_type=Cluster::MANAGER, $ip=127.0.0.1, $p=to_port(getenv("BROKER_PORT1"))],
+	["worker-1"]  = [$node_type=Cluster::WORKER,  $ip=127.0.0.1, $p=to_port(getenv("BROKER_PORT2")), $manager="manager-1", $interface="eth0"],
+	["worker-2"]  = [$node_type=Cluster::WORKER,  $ip=127.0.0.1, $p=to_port(getenv("BROKER_PORT3")), $manager="manager-1", $interface="eth0"],
+};
+@TEST-END-FILE
+
+
+@TEST-START-FILE master.zeek
+redef exit_only_after_terminate = T;
+redef Log::enable_local_logging = T;
+redef Log::default_rotation_interval = 0secs;
+
+module TestModule;
+
+global t: table[string] of count &backend=Broker::MEMORY;
+global s: table[string] of string &backend=Broker::MEMORY;
+
+event zeek_init()
+	{
+	t["a"] = 5;
+	s["a"] = "b";
+	print t;
+	}
+
+event Broker::peer_lost(endpoint: Broker::EndpointInfo, msg: string)
+	{
+	terminate();
+	}
+
+@TEST-END-FILE
+
+@TEST-START-FILE clone.zeek
+redef exit_only_after_terminate = T;
+redef Log::enable_local_logging = T;
+redef Log::default_rotation_interval = 0secs;
+
+module TestModule;
+
+global t: table[count] of count &backend=Broker::MEMORY;
+global s: table[string] of count &backend=Broker::MEMORY;
+
+event dump_tables()
+	{
+	print t;
+	print s;
+	terminate();
+	}
+
+event Cluster::node_up(name: string, id: string)
+	{
+	#print "node up", name;
+	schedule 4secs { dump_tables() };
+	}
+@TEST-END-FILE
diff --git a/testing/btest/broker/store/brokerstore-backend-simple-reverse.zeek b/testing/btest/broker/store/brokerstore-backend-simple-reverse.zeek
index 64e8363730..8ec17e5f32 100644
--- a/testing/btest/broker/store/brokerstore-backend-simple-reverse.zeek
+++ b/testing/btest/broker/store/brokerstore-backend-simple-reverse.zeek
@@ -36,7 +36,7 @@ type testrec: record {
 
 global t: table[string] of count &backend=Broker::MEMORY;
 global s: set[string] &backend=Broker::MEMORY;
-global r: table[string] of testrec &backend=Broker::MEMORY;
+global r: table[string] of testrec &broker_allow_complex_type &backend=Broker::MEMORY;
 
 event zeek_init()
 	{
@@ -67,7 +67,7 @@ type testrec: record {
 
 global t: table[string] of count &backend=Broker::MEMORY;
 global s: set[string] &backend=Broker::MEMORY;
-global r: table[string] of testrec &backend=Broker::MEMORY;
+global r: table[string] of testrec &broker_allow_complex_type &backend=Broker::MEMORY;
 
 event terminate_me()
 	{
@@ -116,7 +116,7 @@ type testrec: record {
 
 global t: table[string] of count &backend=Broker::MEMORY;
 global s: set[string] &backend=Broker::MEMORY;
-global r: table[string] of testrec &backend=Broker::MEMORY;
+global r: table[string] of testrec &broker_allow_complex_type &backend=Broker::MEMORY;
 
 event dump_tables()
 	{
diff --git a/testing/btest/broker/store/brokerstore-backend-simple.zeek b/testing/btest/broker/store/brokerstore-backend-simple.zeek
index f21906302d..6f47e5d3e0 100644
--- a/testing/btest/broker/store/brokerstore-backend-simple.zeek
+++ b/testing/btest/broker/store/brokerstore-backend-simple.zeek
@@ -36,7 +36,7 @@ type testrec: record {
 
 global t: table[string] of count &backend=Broker::MEMORY;
 global s: set[string] &backend=Broker::MEMORY;
-global r: table[string] of testrec &backend=Broker::MEMORY;
+global r: table[string] of testrec &broker_allow_complex_type &backend=Broker::MEMORY;
 
 event zeek_init()
 	{
@@ -79,7 +79,7 @@ type testrec: record {
 
 global t: table[string] of count &backend=Broker::MEMORY;
 global s: set[string] &backend=Broker::MEMORY;
-global r: table[string] of testrec &backend=Broker::MEMORY;
+global r: table[string] of testrec &broker_allow_complex_type &backend=Broker::MEMORY;
 
 
 event dump_tables()
diff --git a/testing/btest/broker/store/brokerstore-backend-sqlite-incompatible.zeek b/testing/btest/broker/store/brokerstore-backend-sqlite-incompatible.zeek
new file mode 100644
index 0000000000..c895a9c6e8
--- /dev/null
+++ b/testing/btest/broker/store/brokerstore-backend-sqlite-incompatible.zeek
@@ -0,0 +1,38 @@
+# @TEST-PORT: BROKER_PORT
+
+# @TEST-EXEC: zeek -B broker -b one.zeek > output1
+# @TEST-EXEC-FAIL: zeek -B broker -b two.zeek > output2
+# @TEST-EXEC: btest-diff .stderr
+# @TEST-EXEC: TEST_DIFF_CANONIFIER=$SCRIPTS/diff-remove-abspath btest-diff .stderr
+
+# the first test writes out the sqlite files...
+
+@TEST-START-FILE one.zeek
+
+module TestModule;
+
+global t: table[string] of string &backend=Broker::SQLITE;
+
+event zeek_init()
+	{
+	t["a"] = "a";
+	t["b"] = "b";
+	t["c"] = "c";
+	print t;
+	}
+
+@TEST-END-FILE
+@TEST-START-FILE two.zeek
+
+# the second one reads them in again. Or not because the types are incompatible.
+
+module TestModule;
+
+global t: table[count] of count &backend=Broker::SQLITE;
+
+
+event zeek_init()
+	{
+	print t;
+	}
+@TEST-END-FILE
diff --git a/testing/btest/broker/store/brokerstore-backend-sqlite.zeek b/testing/btest/broker/store/brokerstore-backend-sqlite.zeek
index 0eb728fe22..1ccbc18c20 100644
--- a/testing/btest/broker/store/brokerstore-backend-sqlite.zeek
+++ b/testing/btest/broker/store/brokerstore-backend-sqlite.zeek
@@ -33,7 +33,7 @@ type testrec: record {
 
 global t: table[string] of count &backend=Broker::SQLITE;
 global s: set[string] &backend=Broker::SQLITE;
-global r: table[string] of testrec &backend=Broker::SQLITE;
+global r: table[string] of testrec &broker_allow_complex_type &backend=Broker::SQLITE;
 
 event zeek_init()
 	{
@@ -71,7 +71,7 @@ type testrec: record {
 
 global t: table[string] of count &backend=Broker::SQLITE;
 global s: set[string] &backend=Broker::SQLITE;
-global r: table[string] of testrec &backend=Broker::SQLITE;
+global r: table[string] of testrec &broker_allow_complex_type &backend=Broker::SQLITE;
 
 redef Broker::auto_store_db_directory = "..";
 
@@ -104,7 +104,7 @@ type testrec: record {
 
 global t: table[string] of count &backend=Broker::MEMORY;
 global s: set[string] &backend=Broker::MEMORY;
-global r: table[string] of testrec &backend=Broker::MEMORY;
+global r: table[string] of testrec &broker_allow_complex_type &backend=Broker::MEMORY;
 
 
 event dump_tables()