chore: add known 6.0 issues

en_US/changes/known-issues-6.0.md

@@ -0,0 +1,7 @@
+# Known Issues in EMQX 6.0
+
+## e6.0.0
+
+| Since version | Issue                                                                                                                                                                                                                                                                                                                                                                                                                                | Workaround                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | Status |
+|---------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|
+| 6.0.0         | **Cannot perform rolling upgrade from cluster running 5.x to 6.0.0 when older bridges are in the configuration**<br /> Clusters that have started running from older EMQX versions that contain the now deprecated `bridges` configuration root will fail to sync their configuration to the new 6.0 nodes, because the latter have dropped for such roots and thus fail to start the corresponding Connectors, Actions and Sources. | Starting from 6.0.1, an RPC call is made to the older node to upgrade the configuration to convert `bridges` into `connectors`, `sources` and `actions`, facilitating rolling upgrades with less manual invervention.<br/>  Alternatively, each affected bridge can be updated via HTTP API or CLI to induce a configuration update (e.g., change the description) which will also upgrade the persisted `cluster.hocon` file.<br/> The following Connector/Sources/Actions might still require manual changes before attempting a rolling upgrade:<br/> - GCP PubSub Consumer and Kafka Consumer: if there are any such sources in the configuration that still contain the `topic_mapping` field, the field must be removed from config and then one Source + Rule pair must be created for each entry. |        |