True with:
"pack_format":3
and
"pack_format":4
See attached. Note: the tested resource packs do not include new textures for terrain, trees, water, sky, etc, so even textures that shouldn't be replaced are wrecked.
Attachments
Comments 2
I traced the actual offending issue down to one invalid file, as detailed in the bug report here:
https://bugs.mojang.com/browse/MC-126062
That one file I had in all my texture packs, so it appeared to me to be all texture packs causing the issue, when in fact it was that one isolated reproducible mcmeta file issue.
The "pack_format" flag is just a flag to signalize to the game that the pack is compatible with versions which require a specific pack format version.
The pack itself still needs to be updated to the new format (most importantly, it may not contain any files with uppercase letters), only changing "pack_format" in the pack.mcmeta file is by far not enough.