What does Windows error code 298 (ERROR_TOO_MANY_POSTS) mean?

ERROR_TOO_MANY_POSTS

What ERROR_TOO_MANY_POSTS means

A semaphore release or post would raise its count beyond the maximum allowed value. The semaphore object exists, but its accounting is already at the configured maximum. This almost always means releases outnumber successful waits or the initial/maximum counts were chosen incorrectly.

Common causes

• A completion path releases the semaphore twice
• A timeout path releases capacity that was never acquired
• Initial count equals maximum and initialization posts again
• Two owners both believe they are responsible for returning the same permit

How to investigate

1. Maintain per-operation acquisition and release counters
2. Log the semaphore count where the API permits it
3. Find paths where errors occur after partial acquisition
4. Use assertions that prevent a logical permit from being returned more than once

Developer guidance

Associate each permit with a scoped token that can be released exactly once. Avoid calling release from independent callbacks unless an atomic state selects the winner.

Administrator and support guidance

Changing the maximum count only hides imbalance. Capture the duplicate release sequence and identify the component that owns permit accounting.

How this code differs from related results

ERROR_TOO_MANY_SEMAPHORES is object-creation exhaustion; this code is count overflow on one existing semaphore.

References

• Microsoft: System error codes 0–499