Firefox: "this add-on could not be installed because it appears to be corrupt"

[DaPa]

Downloading latest zip release (v3.3.0) then drag&drop into Firefox 115.0.3esr (64-bit) on Win 10 Pro 21H2 x64 results in the mentioned message: "this add-on could not be installed because it appears to be corrupt".

After following advice from https://github.com/WaterfoxCo/Waterfox/issues/955#issue-442696152 and appending "applications": { "gecko": { "id": "X@Y" } } at the end of manifest.json, then Firefox only issues a warning "Add HLS Downloader? This extension is unverified..." and if "Add" is pressed, then it accepts to install the extension...

Is this a known issue: can anybody else confirm this?

Current workaround for me:

--- extension-archive-original.zip\manifest.json	2023-07-12 22:26:54.000000000 +0300
+++ extension-archive-changed.zip\manifest.json	2023-07-21 12:30:32.000000000 +0300
@@ -28,4 +28,5 @@
     "128": "assets/icons/128.png",
     "256": "assets/icons/256.png"
-  }
+  },
+  "applications": { "gecko": { "id": "X@Y" } }
 }

[gtubolcev]

Still no joy after adding "applications": { "gecko": { "id": "X@Y" } }. @DaPa could you please upload your manifest.json? Thanks in advance.