Worked for me for paying my Netflix subscription. Edit: Thanks a lot for the warning! I've disabled the 'Ignore X frame' from the extension's menu by default and would only enable it when I'm sure that I'm paying via the correct website.
OK, now it works. I had "new tab override" installed pointing to Google. All worked fine until I updated to Firefox 77.0.1. Then I got the "X frame" error. I loaded Ignore X-frame-option plugin but could not make it work. Then uninstalled both new tab override and ignore X-frame-option. When receiving the developer response I realoaded both and now it works. Not being a Firefox guru, I have NO idea why but now I am very happy bunny. Many thanks.
This was working flawlessly, solving my issue, until the May 3 update, at which point it stopped working. I removed the plug-in and replaced it with the prior version, and all's well. on Firefox 68.6.1esr (64-bit) Mac OS: Mojave 10.14.6
tried adding to github issues page but having login problem. Essentially +1 to issue titled "Error loading some iframe" I'm fine with prior revision, all is truly well with my use case.
I'm realy sorry about that. This last update solve some important issues, and i'd like to help you Can you open an issue there describing as much as you want the issue /your needs ? https://github.com/ThomazPom/Moz-Ext-Ignore-X-Frame-Options/issues