What does Windows error code 8587 (ERROR_DS_THREAD_LIMIT_EXCEEDED) mean?

ERROR_DS_THREAD_LIMIT_EXCEEDED

The thread limit for this request was exceeded.

ERROR_DS_THREAD_LIMIT_EXCEEDED is Win32 error 8587 (0x0000218B).

Likely impact: The DC may still answer lightweight queries while rejecting resource-intensive operations.

Typical causes

• too many concurrent expensive LDAP operations.
• one request fans out into excessive work.
• slow clients keep server work active.
• resource pressure delays worker release.

Troubleshooting steps

1. Verify that the request can obtain a worker without exceeding the configured or internal thread limit.
2. Collect active LDAP request count and operation type and search scope.

Useful evidence

• Collect client connection identities.
• Collect Directory Service performance counters.

Recovery and retry

Reduce concurrent or overly broad operations, cancel stale clients, and retry with bounded concurrency after worker pressure falls.

Related errors

ERROR_DS_OUT_OF_VERSION_STORE concerns retained database versions; this code concerns worker-thread capacity

Example

A client starts hundreds of subtree searches with expensive filters. Limiting concurrency and indexing the filter removes the thread-limit failures.

References

• Microsoft: exact Win32 system error range
• Microsoft: AD DS troubleshooting
• Microsoft: dcdiag
• Microsoft: repadmin