Unlink error messages are not fatal error messages. System Call errors in this context of messaging are simply stating that it was unable to unlink (or delete) a file. The issue here is that when the file was to be deleted, some other process has the file open (file busy). The file can't be deleted until the other process releases the file. The file busy means that it could not be deleted at the time of the unlink call. When the other process releases the file, the file will automatically be deleted because it was marked to be deleted by the previous process.