Below is a list of system error codes from Code 400 to Code 499, along with a description of what the error code means.
Looking for system error codes outside of this range? See my Complete List of System Error Codes for error code details from Code 1 to Code 15299.
Error Code 400
System error code 400 means "The thread is already in background processing mode." This error code may also display as "ERROR_THREAD_MODE_ALREADY_BACKGROUND" or as the value 0x190.Error Code 401
System error code 401 means "The thread is not in background processing mode." This error code may also display as "ERROR_THREAD_MODE_NOT_BACKGROUND" or as the value 0x191.Error Code 402
System error code 402 means "The process is already in background processing mode." This error code may also display as "ERROR_PROCESS_MODE_ALREADY_BACKGROUND" or as the value 0x192.Error Code 403
System error code 403 means "The process is not in background processing mode." This error code may also display as "ERROR_PROCESS_MODE_NOT_BACKGROUND" or as the value 0x193.Error Code 487
System error code 487 means "Attempt to access invalid address." This error code may also display as "ERROR_INVALID_ADDRESS" or as the value 0x1E7.
