ERROR_REPLY_MESSAGE_MISMATCH - 595 (0x253)
{Reply Message Mismatch} An attempt was made to reply to an LPC message, but the thread specified by the client ID in the message was not waiting on that message.
Updated: Feb 21, 2026
Technical Meaning
The ERROR_REPLY_MESSAGE_MISMATCH error code indicates that an attempt was made to reply to a Local Procedure Call (LPC) message, but the thread specified by the client ID in the message was not waiting on that message. This can occur when there is a mismatch between the expected and actual state of threads or messages within the system.
Error Details
The error code 595 (0x253) is specific to situations where an LPC reply operation fails due to an incorrect thread state. LPC is a mechanism used for inter-process communication in Windows, particularly between processes running at different privilege levels.
Usage Context
This error typically occurs in scenarios involving inter-process communication or thread management within the Windows operating system. It can be encountered when attempting to send a reply message over an LPC channel and the target thread is not in the expected state to receive it.
Developer Interpretation
Developers should interpret this error as indicating that there was a failure in the process of replying to an LPC message due to an unexpected or incorrect thread state. This can be caused by various factors, such as incorrect parameter values, timing issues, or mismanagement of threads and messages.
Related Errors
ERROR_INVALID_PARAMETER(0x57)ERROR_THREAD_NOT_WAITING(0x24F)ERROR_NO_SYSTEM_RESOURCES(0x8)
FAQ
Q: What does the ERROR_REPLY_MESSAGE_MISMATCH error mean?
A: This error indicates that a reply to an LPC message was attempted, but the specified thread was not waiting on the message.
Q: How can I troubleshoot this error?
A: Review the context of the inter-process communication and ensure that threads are correctly managed and messages are properly synchronized.
Summary
The ERROR_REPLY_MESSAGE_MISMATCH error code is a specific technical issue related to LPC messaging in Windows. It highlights a failure in thread state management during an attempt to reply to an LPC message. Developers should focus on ensuring correct thread synchronization and proper handling of inter-process communication to avoid this error.