When a user gets error code 1242 in their Yahoo mail then there could be many possible reasons behind the error code 1242 of Yahoo mail and some of them are listed in this forum.

1. Unauthorised attack of virus, malware or spyware.

2. Suspicious activity

3. Improper or incomplete installations of some applications.

4. Deletion of important windows files.

5. Windows files are getting corrupted.

Also Read - https://writeapp.me/online-geeks/note/how-to-fix-yahoo-mail-error-code-1242