MSBuild bug (kinda...)

· January 17, 2007

At the start of this year my buildscripts ran into some serious trouble all of a sudden. And the day after this ugly error showed its horrible face when I compiled the code:

"Error emitting 'System.Reflection.AssemblyVersionAttribute' attribute -- 'The version specified '1.6.70102.1' is invalid"

What now? I know that nobody was here and changed code during the New Years Eve, and certainly not the day after, if you know what i mean.

It proves to be a flaw (nicer way of saying bug) in the assembly version handling of MSBuild, or actually the versioning of assemblies in Windows:

The version numbers consist of four parts MAJOR.MINOR.BUILD.REVISION. These are all WORDS (16-bit) and not DWORD (32-bit). That means that it can hold numbers up to ca 65000.

A very common practice is to have the BUILD-part of the number set to a date. And since dates are converted like so:

2007-01-01 -> 070101 -> 70101

we can clearly see that 70101 is a bigger number than 65000.

So here you have it - the MSBuild-version of the Y2k-problem but rather Y2007-problem to be exact.

The solutions are plentiful and very innovative, for example:

But they all suffer from the flaw that you need to distribute any solution to all the computers that ever build the solution (i.e. the developers).

My solution is to just increment the build-number and not base it on dates. This is not too good either but works for now

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