Validation failed for one or more entities. See 'EntityValidationErrors' property for more details [duplicate]

Answer 1

If you're using IIS with Windows Authentification and Entity Framework, be careful to use authorize.

I tried to POST without authorize and it didn't work, and get this error on db.SaveChangesAsync();, while all other verbs GET and DELETE were working.

But when I added AuthorizeAttribute as annotation, it worked.

[Authorize]
public async Task Post(...){
....
}