What does Windows error code 15203 (ERROR_MCA_MCCS_VERSION_MISMATCH) mean?

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: Two monitor reports disagree about the MCCS version.

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ERROR_MCA_MONITOR_VIOLATES_MCCS_SPECIFICATION	ERROR_MCA_UNSUPPORTED_MCCS_VERSION

ERROR_MCA_MCCS_VERSION_MISMATCH

Two independent answers disagree

This error is narrower than a generic MCCS compliance failure. Windows obtained a version from the monitor's capability string, normally in mccs_ver(...), and another from a VCP Feature Request for 0xDF. Both answers are intended to describe the same monitor-control revision. When they differ, software cannot safely select the version-specific interpretation of VCP features from either claim alone.

Why the distinction matters

VCP feature classifications and values evolve across MCCS revisions. A feature that is discrete in one revision can have a different representation in another. Tools such as ddcutil therefore distinguish the monitor-provided capabilities text from a direct VCP version query, and document that real displays sometimes report inconsistent information. This is why a string that looks syntactically valid can still produce a version mismatch.

Verification checklist

Fetch the exact ASCII capabilities string and save it unchanged.
Read 0xDF from the same physical monitor handle during the same test session.
Confirm that the display was not switched through a KVM, dock, adapter, or input change between the two requests.
Record monitor model and firmware revision. The useful remediation is often a firmware or vendor-control update, not a random application retry.

Do not resolve the discrepancy by editing the parsed version in application memory. That can hide the error while causing later VCP values to be decoded according to the wrong MCCS revision.

References

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