Issues compiling label files

Yesterday evening (why does it always have to be evenings ;-) ) I was going to do a deploy of code to our staging environment. I started the build in Azure Devops and it failed:

C:\DynamicsSDK\Metadata\Microsoft.Dynamics.AX.Application.Build.targets(78,5): error MSB6006: “LabelC.exe” exited with code -1. [C:\DynamicsSDK\Metadata\BuildMetadata.proj]

OK… SO LabelC.exe atleast gives me some hints and since the deployconsisted of changes to Label Files this was not too strange. I downloaded the log file and found this information:

outlog=C:\DynamicsSDK\VSOAgent_work\10\Logs\ModelName\Dynamics.AX.ModelName.labelc.log

So I looked in the log file on the build server and found the following:

The error was duplicate lines in two label files

Remove them by editing the file in Azure DevOps and check in the file. Restart the build and it worked… Way