Hi digitatum, Firefox 68 contains a security patch which restricts the kinds of files that pages can load (and methods of loading) when you open them '''from a file:// URL'''. This change was made to prevent exfiltration of valuable data within reach of a local page, as demonstrated in an available exploit. More info: * https://developer.mozilla.org/docs/Web/HTTP/CORS/Errors/CORSRequestNotHttp * https://www.mozilla.org/security/advisories/mfsa2019-21/#CVE-2019-11730 There will be an exception in Firefox 70 for font files; that might also make it into Firefox 69. For now, through, you could consider rolling back the patch as follows: (1) In a new tab, type or paste '''about:config''' in the address bar and press Enter/Return. Click the button promising to be careful or accepting the risk. (2) In the search box above the list, type or paste '''uniq''' and pause while the list is filtered (3) Double-click the '''privacy.file_unique_origin''' preference to switch the value from true to false To mitigate the vulnerability: If you save pages from untrusted sites in a separate folder, e.g., Downloads\Untrusted, then it would be difficult for an attacker to find any valuable content using local file links.