"Illegal characters in path" error when building UWP project with SQLite extension on VSTS Hosted agent

When using a Hosted agent to build my UWP application on VSTS I'm getting an error:

_GenerateAppxSymbolPackage:
C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v14.0\AppxPackage\PDBCopy.exe C:\a\1\s\App\MyApp\bin\ARM\Debug\BordersApp.pdb obj\ARM\Debug\Stripped\BordersApp.pdb 
C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v14.0\AppxPackage\PDBCopy.exe C:\a\1\s\App\Extensions\UAP\v0.8.0.0\ExtensionSDKs\SQLite.UWP.2015\3.11.1\Redist\Debug\ARM\sqlite3.pdb obj\ARM\Debug\Stripped\sqlite3.pdb 
##[error]C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v14.0\AppxPackage\Microsoft.AppXPackage.Targets(2550,5): Error APPX0002: Task 'GenerateAppxSymbolPackage' failed. Illegal characters in path.

Any ideas / hints on what might be wrong with those paths? Or is it some bug in VSTS?