I know banks like Chase and Citi has fairly recently required Firefox 128.0 or later to use the sites. Since you appear to have the eol macOS 10.14 the most current version you can run is Firefox 115 ESR currently at 115.31.0esr. Firefox 116.0 and later requires macOS 10.15 or later to run. https://support.mozilla.org/en-US/kb/firefox-users-macos-1012-1013-1014-moving-to-extended-support If you cannot update your macOS to 10.15 (ten.fifteen) or later to use the current Firefox versions, then there is something you can try to fool the bank sites into thinking you have a more current version. # In a new tab, type or paste '''about:config''' with a colon : in the Location (address) bar and press Enter/Return. Click the button accepting the risk. # In the search box on top of the page, type or paste forceVersion and pause while the list is filtered # Double-click the ''network.http.useragent.forceVersion'' preference to display an editing field, and change the value to '''128''' or '''140''' then press Enter/Return or click the blue check mark button to save the change.