Error MSB6006: “mt.exe” exited with code 31

Question

I ran into this problem today while migrating a VS2008 solution to VS2010. The problem occurred in either of the following scenarios:

1. Rebuild Solution

Answer 1

In my projects, the Intermediate and Output directories were set to:

• Intermediate Dir : $(Configuration)\
• Output Dir : $(SolutionDir)bin\$(Configuration)\

Under C/C++-->Output Files, I had the following:

• ASM List Location : $(IntDir)\
• Object File Name : $(IntDir)\
• Program Database File Name : $(OutDir)\$(TargetName).pdb

Under Linker-->Manifest File, I had:

• Manifest File : $(IntDir)$(TargetName)$(TargetExt).intermediate.manifest

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The cure was to remove the trailing \ from my C/C++-->Output Files section (because it's already part of those variables):

• ASM List Location : $(IntDir)
• Object File Name : $(IntDir)
• Program Database File Name : $(OutDir)$(TargetName).pdb

Normally, the double-up of using $(IntDir) or $(OutDir) with a trailing \ doesn't seem to cause trouble, even though it's bad practice. I can't remember now whether I did it by accident or if the conversion process did it, but for whatever reason, it seems to have been messing up MT.exe.

I hope this is useful to anyone else who encounters this problem. Your settings may well be different, but consider that it may be related to improperly formed filenames.