Incompatible unmet requirements Exists=>MSBuildTools18\.0_.+_Path exists (= FALSE)

Symptoms

Builds don't start due to incompatible unmet requirements: Exists=\>MSBuildTools18.0_.+_Path exists (= FALSE)

Cause

The MSBuildTools18.0_*_Path parameter detection broke with a Visual Studio 2026 update to version 18.10.0.

Workaround

• Roll back Visual Studio 2026 to version 18.9.3. or

• Add these entries in the <agent_home>\conf\buildAgent.properties file and allow the agent to restart:

  # TW-104025 workaround
  MSBuildTools18.0_x64_Path=%MSBuildTools0.0_x64_Path%
  MSBuildTools18.0_x86_Path=%MSBuildTools0.0_x86_Path%
  # If the agent machine is ARM
  MSBuildTools18.0_ARM64_Path=%MSBuildTools0.0_ARM64_Path%
  

  Note: these would have to be removed later.

Resolution

For a long-term solution, follow the bug report TW-104025.