Fixing invalid version number problems with the AssemblyInfoTask

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The arrival of 2007 bought a flurry of e-mails to the MSBuild team from people having trouble with the AssemblyInfoTask. The symptom is simple to describe - the builds start to fail with the following error:

Error emitting 'System.Reflection.AssemblyVersionAttribute' attribute -- 'The version specified '1.0.70102.1' is invalid

The fix to get builds going again is to change the date format used to generate the build number to something other than the default "yyMMdd". The date formats are in Microsoft.VersionNumber.target, located in %program files%\MSBuild\Microsoft\AssemblyInfoTask, and there are two of them (one for file version and one for assembly version). You can use any format you want. Within Visual Studio we're now using 01MMdd.

Note that you may have to go in and hand-edit your assemblyinfo.* files to change their version number back to a default starting point of 1.0.0.0 to get your builds going again.

Questions or problems after doing the above? Contact us using the e-mail link at the top of this page.

[ Author: Neil Enns ]