This could be about a new security feature that blocks unsafe downloads, but can interfere with downloading files. You can set dom.block_download_insecure => false in about:config to disable this feature.

• https://support.mozilla.org/en-US/kb/about-config-editor-firefox

Hi Raymond, I assume this is a verification issue like certificate issuer not recognized and not the red warning page shown when a site is considered malicious based on Google SafeBrowsing data. If you could copy/paste the text of the error page into a reply (here on the forum, not by email), that would be helpful.

Normally if you go through the Accept button and then click Accept the Risk and Continue, the site certificate is saved permanently (in the cert9.db file in your Firefox profile). You should be able to see it on the Settings page:

• Open the Settings page
• Slowly type cert in the tiny search box until Firefox brings the View Certificates... button into view
• Click the "View Certificates..." button to open the Certificate Manager dialog
• Change to the Servers list -- do you see your exception(s) saved here?

Firefox might not save the certificate permanently if (A) you are using a private window, or (B) you set security.certerrors.permanentOverride to false in about:config.