An error occurred while trying to write data to the specified file for use by an agent running on the same host as emake itself. The OS error message provides the specific cause of the failure. Note that this is not considered a fatal error since emake can try to run the associated build job on a different agent.
Because the error involves an external system in this context (the filesystem on the emake host), the list of possible causes for this error is virtually limitless: a corrupted filesystem; hardware failure; insufficient permissions; and so on. Refer to the specific OS error message to determine the cause of the failure.