This error just seems to happen randomly. I've done an internet search, but nothing turns up. If I clean out the bin, obj, and .vs directories, it will fix it for a few builds and then the error will come back.
1>------ Build started: Project: GridViewOnly, Configuration: Debug Any CPU ------
1>Failed to check the content hash of the destination ref assembly 'C:\Users\myuser\source\repos\GridViewOnly\bin\Debug\net5.0-windows\ref\GridViewOnly.dll'. It will be overwritten.
1>C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\MSBuild\Current\Bin\Microsoft.Common.CurrentVersion.targets(4413,5): error MSB4018: The "CopyRefAssembly" task failed unexpectedly.
1>C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\MSBuild\Current\Bin\Microsoft.Common.CurrentVersion.targets(4413,5): error MSB4018: System.InvalidOperationException: The "CopyRefAssembly" task has not registered its resources. In order to use the "TaskLoggingHelper.FormatResourceString()" method this task needs to register its resources either during construction, or via the "TaskResources" property.
1>C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\MSBuild\Current\Bin\Microsoft.Common.CurrentVersion.targets(4413,5): error MSB4018: at Microsoft.Build.Shared.ErrorUtilities.ThrowInvalidOperation(String resourceName, Object[] args)
1>C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\MSBuild\Current\Bin\Microsoft.Common.CurrentVersion.targets(4413,5): error MSB4018: at Microsoft.Build.Shared.ErrorUtilities.VerifyThrowInvalidOperation(Boolean condition, String resourceName, Object arg0)
1>C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\MSBuild\Current\Bin\Microsoft.Common.CurrentVersion.targets(4413,5): error MSB4018: at Microsoft.Build.Utilities.TaskLoggingHelper.FormatResourceString(String resourceName, Object[] args)
1>C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\MSBuild\Current\Bin\Microsoft.Common.CurrentVersion.targets(4413,5): error MSB4018: at Microsoft.Build.Utilities.TaskLoggingHelper.LogErrorWithCodeFromResources(String messageResourceName, Object[] messageArgs)
1>C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\MSBuild\Current\Bin\Microsoft.Common.CurrentVersion.targets(4413,5): error MSB4018: at Microsoft.CodeAnalysis.BuildTasks.CopyRefAssembly.Copy()
1>C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\MSBuild\Current\Bin\Microsoft.Common.CurrentVersion.targets(4413,5): error MSB4018: at Microsoft.CodeAnalysis.BuildTasks.CopyRefAssembly.Execute()
1>C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\MSBuild\Current\Bin\Microsoft.Common.CurrentVersion.targets(4413,5): error MSB4018: at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
1>C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\MSBuild\Current\Bin\Microsoft.Common.CurrentVersion.targets(4413,5): error MSB4018: at Microsoft.Build.BackEnd.TaskBuilder.<ExecuteInstantiatedTask>d__26.MoveNext()
1>Done building project "GridViewOnly.csproj" -- FAILED.
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========