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Firefox crashes when paying with Paypal

Pseudoryx

Recently I cannot use Paypal to process any online payment on Firefox without the browser crashing.

OS: Windows 11 25H2 Reproduction steps: a vendor would have a Paypal button. I would click on it and Firefox would open a pop-up window briefly before crashing.

The pop-up window is normal behaviour for how Paypal processing has worked on Firefox in the past. I have tried turning off potential content blockers: 3rd-party userscripts loading through ViolentMonkey, content blockers via AdNaseaum, and Enhanced Tracking Protection to no effect.

Recently I cannot use Paypal to process any online payment on Firefox without the browser crashing. OS: Windows 11 25H2 Reproduction steps: a vendor would have a Paypal button. I would click on it and Firefox would open a pop-up window briefly before crashing. The pop-up window is normal behaviour for how Paypal processing has worked on Firefox in the past. I have tried turning off potential content blockers: 3rd-party userscripts loading through ViolentMonkey, content blockers via AdNaseaum, and Enhanced Tracking Protection to no effect.
Lees dié antwoord in konteks

Gekose oplossing

Thanks to @jbr outlining some additional troubleshooting steps, I have managed to identify the issue myself.

The crash is being caused by a userChrome.js. The javascript has worked with Firefox for a long time but looks like it's crashing the more recent versions. https://github.com/aminought/firefox-second-sidebar

All Replies (6)

This looks like a useful Firefox support discussion for anyone experiencing a similar issue. It would be helpful to include the Firefox version, operating system, and any troubleshooting steps already attempted so other users can narrow down the cause more easily.

I quickly checked in clean 155, 156 and 158 nightlies from the past few days and don't see an issue. I'll add some reproduction/verification scenario in a bit. (These popups are infamous for their cross–frame cross–origin opener into about:blank with delayed writing of the destination, but I don't see any crash to that tune trying out the reproduction steps.)

There is a reduced test case for the above at https://firefox-demo.fly.dev/ if you fancy trying to crash there as well.

If would help to see the crash logs if they get uploaded: (and ideally, from a clean profile, or restarted into troubleshoot mode to eliminate customizations…)

  1. Enter about:crashes in the Firefox address bar and press Enter. A list of Submitted (and Unsubmitted, if any) Crash Reports will appear, similar to the one shown below.
  2. Copy the 5 most recent Submitted Report IDs that start with bp- and then go back to your forum question and paste those IDs into the "Post a Reply" box.

Note: If a recent Report ID does not start with bp- click on it to submit the report.

(Please don't take a screenshot of your crashes, just copy and paste the IDs. The below image is just an example of what your Firefox screen should look like.)

Fx115aboutcrashes

Thank you for your help!

Gekose oplossing

Thanks to @jbr outlining some additional troubleshooting steps, I have managed to identify the issue myself.

The crash is being caused by a userChrome.js. The javascript has worked with Firefox for a long time but looks like it's crashing the more recent versions. https://github.com/aminought/firefox-second-sidebar

I see it's now filed in github.com/aminought/firefox-second-sidebar/issues/212 — good call!

If you share the crash log IDs here I can at least try to cross–reference them to any sec–bug fixes that might have introduced new isolated processes' hardening, in case there's a known pattern already.

jbr said

I see it's now filed in github.com/aminought/firefox-second-sidebar/issues/212 — good call! If you share the crash log IDs here I can at least try to cross–reference them to any sec–bug fixes that might have introduced new isolated processes' hardening, in case there's a known pattern already.

Thank you. Here are the crash log IDs of the five latest crashes.

  • bp-eddafc69-93bd-4894-a06a-c485d0260914
  • bp-cb177f57-aa47-481e-9148-abf1d0260914
  • bp-ddc03a85-b2aa-4f11-86d4-4997a0260914
  • bp-ff82898e-3680-423c-bf35-d9c450260914
  • bp-955f3a22-701a-4d44-8496-b773a0260914

Aaah, yeah, so that's something with target=_blank — I'll read through the timeline of bugzilla.mozilla.org/1954236 and if I find any interesting notes to share with the authors I'll add it to the issue linked. Thanks!

Vra 'n vraag

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