MSB3245
This diagnostic code is emitted when MSBuild can't resolve an assembly reference in your project.
The full message resembles the following text:
MSB3245: Could not resolve this reference. 'assembly' If this reference is required by your code, you may get compilation errors.
This error might occur if the item is a directory, not a file, or it could occur if the assembly resolver for that reference returns an error. It could be any error that prevents resolution of the reference, such as a missing assembly, misspelled name, version mismatch, mismatched processor architecture, or failed ProjectReference.
For a guide on resolving errors with assembly references, see Troubleshoot assembly references.