+++ This bug was initially created as a clone of Bug #1532530 +++

User Agent:Mozilla/5.0 (X11; Linux x86_64; rv:71.0) Gecko/20100101 Firefox/71.0
Version: 71.0b8
Build ID: 20191107101713

Steps to reproduce:

1. Install an empty webRequest.onBeforeUpload listener with requestBody option (see the webRequest_requestBody/web-ext-artifacts/webrequest_requestbody_bug_non_binary_big_uploads-1.xpi extension in the attached zip)
2. Attempt a multipart form submission whose non-binary (non file) data amounts to more than 1MB (e.g. by running the server.js NodeJS test server in the attached zip and browsing it at https://localhost:5000 )

Actual results:

The submission stalls and never completes.
On Trunk (build ID 20191111100226) the tab usually crashes even without any extension installed, probably because a different (but likely related) IPL bug, see https://crash-stats.mozilla.org/report/index/9675a718-8e79-4937-8959-db1780191111.

Expected results:

The submission should complete normally.

(In reply to Giorgio Maone [:mao] from comment #0)

On Trunk (build ID 20191111100226) the tab usually crashes even without any extension installed, probably because a different (but likely related) IPL bug, see https://crash-stats.mozilla.org/report/index/9675a718-8e79-4937-8959-db1780191111.

Please file a necko bug for this.

I'll look at this bug in two weeks. Meanwhile, could you answer the following questions?

1. Is this bug consistently reproducible with the given STR?
2. Is this a regression?