User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:65.0) Gecko/20100101 Firefox/65.0 Steps to reproduce: I opened this page to test the new webp support http://littlesvr.ca/apng/gif_apng_webp.html and I activated webp support in about:config Actual results: Test 2 works fine Test 5 the lossy webp animation has a few glitches when the animation repeats itself Test 1, 3 and 4 crash the tab, once one cycle of the animation completes all tests don't load the webp file on page load for some reason (it needs opening the link manually or switching to another test and back to make them show up) Direct file link to test 1 http://littlesvr.ca/apng/images/GenevaDrive.webp

I'm using Windows 10 Education edition 64bit with the current 64bit nightly of Firefox. I tested this using a fresh profile. I'm fairly certain that this bug blocks: https://bugzilla.mozilla.org/show_bug.cgi?id=1294490 So I just added that info to this bug

Bug 1503935 probably fixed the crashes, it just landed, should be in tomorrow's nightly, or maybe the one after that.

The newly minted nightly 20181102100039 and onwards should contain the fix for this problem :). Please reopen if you encounter it again.