Lately I’ve been getting more and more this type of error from Nuget Package Restore when building my apps:
This seems to be a completely random issue with Nuget, as I see it happening with different projects, and sometimes not even happening at all!
Problem is that I work with some big/complex solutions that have a lot of projects, each one with it’s own packages.config file that can show this issue, so that sums up to a lot of failed builds!
There are actually a few open tickets about this in Codeplex, but given that this issue has been reported a while ago and so far it has not been solved, I thought on tackle this myself!
“If at first you don’t succeed, try and try again”
Following that motto, I thought on changing the Nuget Package Restore process so that it will retry a few times before aborting the build!
The easiest way I found to achieve this goal is just to change the .nuget\NuGet.targets file on the root of the solution. Inside this file, I found the following:
<Target Name="RestorePackages" DependsOnTargets="CheckPrerequisites">
<Exec Command="$(RestoreCommand)"
Condition="'$(OS)' != 'Windows_NT' And Exists('$(PackagesConfig)')" />
<Exec Command="$(RestoreCommand)"
LogStandardErrorAsError="true"
Condition="'$(OS)' == 'Windows_NT' And Exists('$(PackagesConfig)')" />
</Target>
Above you can see the MSBuild target that actually runs Nuget.exe, and so this is the one I will change to “fix” the issue.
This is my improved RestorePackages target:
<Target Name="RestorePackages" DependsOnTargets="CheckPrerequisites" Condition="Exists('$(PackagesConfig)')">
<PropertyGroup>
<NugetLogStandardErrorAsError Condition="'$(OS)' == 'Windows_NT'">true</NugetLogStandardErrorAsError>
<NugetLogStandardErrorAsError Condition="'$(OS)' != 'Windows_NT'">false</NugetLogStandardErrorAsError>
</PropertyGroup>
<Exec Command="$(RestoreCommand)" LogStandardErrorAsError="$(NugetLogStandardErrorAsError)" IgnoreExitCode="True">
<Output TaskParameter="ExitCode" PropertyName="ExitCode" />
</Exec>
<Message Text="Error occurred, #1 retry..." Importance="High" Condition=" $(ExitCode) != 0 " />
<Exec Command="$(RestoreCommand)" LogStandardErrorAsError="$(NugetLogStandardErrorAsError)" IgnoreExitCode="True" Condition=" $(ExitCode) != 0 ">
<Output TaskParameter="ExitCode" PropertyName="ExitCode" />
</Exec>
<Message Text="Error occurred, #2 and last retry..." Importance="High" Condition=" $(ExitCode) != 0 " />
<Exec Command="$(RestoreCommand)" LogStandardErrorAsError="$(NugetLogStandardErrorAsError)" Condition=" $(ExitCode) != 0 " />
</Target>
You can see three consecutive Exec tasks here, each one will run depending on the previous one exit code, and only the last one will actually abort the build.
What this means is that if Nuget fails, we will retry it two more times before aborting the build!
As you can see, this is not a proper fix for the issue, it just bypasses it… so I’m still waiting for a fix on this - and I’m now looking at you, Nuget dev team! ;)
