Firefox 96 made some major changes related to cookies. The changes were intended to match Chrome and Edge, but obviously there is some subtlety or exception list that was overlooked. There is one in particular that seems to affect bank and credit union sites where the second site depends on some credentials from the first site. Here are some settings you can tweak: (A) In a new tab, type or paste '''about:config''' in the address bar and press Enter/Return. Click the button accepting the risk. ''More info on about:config:'' [[Configuration Editor for Firefox]]. ''The moderators would like us to remind you that changes made through this back door aren't fully supported and aren't guaranteed to continue working in the future.'' (B) In the search box in the page, type or paste '''laxByDefault''' and pause while the list is filtered ''Firefox should list two matching preferences:'' * network.cookie.sameSite.laxByDefault * network.cookie.sameSite.laxByDefault.disabledHosts '''Scenario #1: You have a few extra minutes to help me with a test''' (C) Double-click the '''network.cookie.sameSite.laxByDefault.disabledHosts''' preference to display an editing field, and enter the host name of the external transfers server. Then press Enter or click the blue check mark button to save the change. As an example, let's say the address of the site2 server is https://''www.bigprocessing''.''com''/somefolder/somepage.html. In the preference, enter ''www.bigprocessing''.''com'' as your host that is exempt from the policy. (If there already is another host name listed in this preference, separate them with a comma.) Can you access the external transfer service after that? (I don't know whether that takes effect immediately or whether you need to quit Firefox and start it up again.) '''Scenario #2: You need an immediate fix even if it's less secure AND/OR the earlier test didn't work''' (D) Double-click the '''network.cookie.sameSite.laxByDefault''' preference to switch the value from true to false Can you access the external transfer service after that? (I don't know whether that takes effect immediately or whether you need to quit Firefox and start it up again.)