What does Windows error code 614 (ERROR_NO_CALLBACK_ACTIVE) mean?

ERROR_NO_CALLBACK_ACTIVE

A callback return system service cannot be executed when no callback is active.

ERROR_NO_CALLBACK_ACTIVE is Windows system result 614 (0x00000266). Microsoft defines it as “A callback return system service cannot be executed when no callback is active.”

How to classify the result

This result represents an invalid callback-return state transition. The correct interpretation depends on the thread and callback mechanism that should have established an active callback frame before the return service was invoked.

Where it can appear

• This result can appear in a subsystem callback crossing a user/kernel or client/server boundary.
• This result can appear in compatibility code that wraps a low-level callback-return service.
• It can appear in instrumentation or hooking code that disturbed callback stack discipline.

Typical causes

• the callback-return routine was called outside its callback.
• the thread changed before the return path executed.
• an exception or long jump skipped callback bookkeeping.
• a hook invoked the return service twice.
• stack corruption damaged the active callback state.

Useful evidence

• Record callback type and owner.
• Record entry and return thread IDs.
• Record entry and return stack pointers.
• Record exception or hook activity between entry and exit.
• Record crash dump or trace at the first invalid return.

Recovery and retry

Restore balanced callback entry and return control flow; remove any second return, cross-thread handoff, or stack switch not supported by the callback contract.

This state error is deterministic. Retry cannot create the missing callback frame and can worsen corruption; stop the operation and fix the control-flow defect.

Difference from related results

It is not the same as a user APC not running. It specifically rejects a callback-return service because no matching callback is active.

Example

A hook catches an exception inside a subsystem callback and directly invokes the callback-return helper after the normal unwinder has already removed the frame. A debugger breakpoint shows the second return and identifies the hook.

Developer and administrator guidance

Treat this value as a programming or corruption signal, not a transient service outage. Production telemetry should capture a dump or at least a stack hash on the first occurrence.

References

• Microsoft: System Error Codes 500–999
• Microsoft Open Specifications: Win32 error values
• Microsoft: Application Verifier