The SSL_ERROR_NO_CYPHER_OVERLAP error in Firefox usually occurs when there is a problem with the encryption settings between the browser and the web server. Here are some steps you can take to fix the error:
Clear your browser cache and cookies: Sometimes the error is caused by corrupted or outdated browser data. Clearing your cache and cookies can help resolve this issue.
Check the website's SSL certificate: Make sure the website's SSL certificate is valid and up-to-date. You can check this by clicking on the padlock icon in the address bar and selecting "More Information" or "View Certificate".
Disable SSL scanning in your antivirus software: Some antivirus software may interfere with SSL encryption and cause the error. Try disabling SSL scanning in your antivirus settings and see if that resolves the issue.
Try a different browser: If the error persists, try accessing the website in a different browser to see if the issue is specific to Firefox.
Contact the website's administrator: If none of the above steps resolve the issue, contact the website's administrator and ask them to check their SSL configuration.
Hopefully one of these steps will help you fix the SSL_ERROR_NO_CYPHER_OVERLAP error in Firefox.