+++ This bug was initially created as a clone of Bug #1356300 +++

(Hmm, what happened here, some gremlin hit enter and created the bug before I typed in all the details). The GIF image in attachment 8858340 [details] cannot be added as background. Steps are described in bug 1356300 comment #5. I can reproduce the problem with this image in TB 52 ESR, however, it works correctly in TB 55 Daily. So that will be hard to locate :-)

Alice, I have another job for you ;-) The image in attachment 8858340 [details] "Rosechain_inline plus.gif (GIF Image, 407 × 766 pixels)" cannot be used as background image in TB in TB 52 ESR: - Open compose window - Format > Page Colors and Background - Select the file - OK - doesn't work. Works fine in TB 55. Can you find where this got fixed?

An error shown when click [OK] TypeError: File.createFromNsIFile(...).then is not a function[Learn More] EdColorPropsOverlay.xul:26:9 Regression window: https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=47e0584afe0ab0b867412189c610b302b6ba0ea7&tochange=1196bf3032e1bce1fb07a01fd9082a767426c5fb Suspect: 938f7fd2ce2b Andrea Marchesini — Bug 1303518 - Remove the chrome only constructor for File, r=qdot

Aha, you requested fixed range... Wait

I know when that got fixed: Bug 1348663 ;-) And that got uplifted to TB 52: https://hg.mozilla.org/releases/comm-esr52/rev/33b3cac977d8c66e2e649176f691eddec3ddd573 So why doesn't that work?

Damn, https://hg.mozilla.org/releases/comm-esr52/rev/33b3cac977d8c66e2e649176f691eddec3ddd573 fixed an issue that ported two bugs: Bug 1338138 - Make call to createFromNsIFile() async (port bug 1335536 to mail). r=mkmelin - mozilla54!! Bug 1303518. So for TB 52 this would have been right: - let file = new File(nsFile); + let file = File.createFromNsIFile(nsFile); But tacking the async .then() at the end is wrong and will only work from mozilla54.

Will be fixed by correcting the uplift in bug 1348663, see bug 1348663 comment #8. Thanks again, Alice and Anje for reporting!!