There are two kinds of EFile errors, error code 184, and error code other than 184. Read carefully here:
If you get an error code other than 184, please refer to this document or call the CRA helpdesk to find out what the problem is. The reasons most likely are your EFILER ID/password are not matching CRA records, or you are not fully approved to submit EFILE or your EFILER account is locked, etc. Here is the page with all the error codes.
CRA website: Chapter 2 EFILE Error Messages for 2017 to 2022
or you can check the copy we host (may not contain the latest codes):
If you see error code 184, you will also see some error clue codes in the efile result. please read this FAQ link.