When you try to build your project, MSBuild (the build engine) attempts to access or overwrite this DLL. If another process has already loaded it, Windows blocks MSBuild, resulting in the error you see.
Find -> Find Handle or DLL -> "microsoft.bcl.build.tasks.dll" microsoft.bcl.build.tasks.dll is used by another process
: By default, MSBuild keeps "worker nodes" (processes) alive after a build to speed up subsequent tasks. These processes often hold onto loaded DLLs. Parallel Builds When you try to build your project, MSBuild
The Microsoft.Bcl.Build package is often a dependency for older libraries like Microsoft.Net.Http . Check the for updates. Newer versions have better handling of task execution and file locking. Check for Ghost Visual Studio Instances Windows blocks MSBuild