Azure AD Connect Sync fails with Event ID 6311

Azure AD Connect Sync fails to synchronise with Event ID 6311

Issue

ADSync Event ID 6311 in the Application event log

The server encountered an unexpected error while performing a callback operation.

"BAIL: MMS(4472): X:\bt\1011518\repo\src\dev\sync\shared\framework_mixedmodeutils\CompressionUtils.cpp(371): 0x80004005 (Unspecified error): Unicode surrogate characters must be written out as pairs together in the same call, not individually. Consider passing in a character array instead.BAIL: MMS(4472): ..\exechist.cpp(790): 0x80004005 (Unspecified error)
BAIL: MMS(4472): X:\bt\1011518\repo\src\dev\sync\server\mastate\mastate.cpp(8114): 0x80004005 (Unspecified error)
WARNING: MMS(4472): ..\ma.cpp(5182): Could not add execution history 0x80004005
BAIL: MMS(4472): ..\ma.cpp(5190): 0x80004005 (Unspecified error)
Azure AD Sync 1.3.21.0"

Synchronization Service Manager shows job failed with “completed-sync-errors” however there are no status or error messages in the lower pane. Any additional tasks such as export tasks will not run after this failed task.

Cause

Azure AD Connect Sync cannot synchronise when unicode characters are present and there is an issue with the object preventing sync such as a description field over 255 characters.

This appears to only be an issue when both conditions are true.

Solution

One off fix

Temporarily remove the unicode character, and also fix the import/export error from the failing object and resync.

To find the object which has an issue

• Click the Connectors Tab
• Right click the connector and click “Search Connector Space”
• Change the scope to Import Errors
• Click Search
• Repeat for Export Errors scope
• Repeat for each connector

Resolve the issues with the objects and temporarily remove unicode characters. Once the sync is successful the unicode characters can be re-added.

Real fix

Upgrade to a newer version of Azure AD Connect Sync. Version 1.4.25.0 appears to have fixed this exact issue. Note, I have not tested a newer version yet but the Microsoft guidance suggests that this is resolved.

Fixed issues
Under certain circumstances, servers that were auto upgraded to version 1.4.18.0 did not re-enable Self-service password reset and Password Writeback after the upgrade was completed. This auto upgrade release fixes that issue and re-enables Self-service password reset and Password Writeback.

We fixed a bug in the sync errors compression utility that was not handling surrogate characters correctly.

Azure AD Connect Sync version history

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