Fails to install

[GerryOnGithub]

Package is invalid: CRX_REQUIRED_PROOF_MISSING

[nicolaasjan]

Same here.

When I click on the icon in the toolbar, the extension downloads, but when I drag it in the extensions page nothing happens...

[NeverDecaf]

Which browser, version, and extension? Also, ensure you have developer mode enabled as installing from .crx will always fail without it. As a last resort you can try Load Unpacked after extracting the .crx file to a folder.

[nicolaasjan]

Which browser, version, and extension? Also, ensure you have developer mode enabled as installing from .crx will always fail without it. As a last resort you can try Load Unpacked after extracting the .crx file to a folder.

Browser & version: Ungoogled-Chromium 80.0.3987.149-1.bionic1
Extension: chromium-web-store 0.8.1
Developer mode is enabled.

I can't extract the .crx on my system (Linux Mint 19.3; Engrampa archive manager)

[EDIT]
I managed to extract it via the commandline:
unzip Chromium.Web.Store.crx
Then put the files in a folder in my home directory and loaded the unpacked extension.
That worked, but shouldn't be necessary IMHO...

[NeverDecaf]

I mistakenly thought the issue was with installing other extensions via chromium-web-store. I agree that the developer mode load unpacked workaround shouldn't be necessary but unfortunately Google does not. It is by design that you cannot normally install extensions from anywhere besides the Chrome Web Store.
That being said, drag-and-drop installation of unsigned .crx files in dev. mode does work for me and presumably other users of ungoogled chromium, so it may be an issue with your particular build. I will leave this issue open for a while in case somebody with a similar setup can offer help.

[NeverDecaf]

see: ungoogled-software/ungoogled-chromium#923 (comment)

[sasanj]

Same Here:
MacOS Catalina
Ungoogled Chromium Version 80.0.3987.163 (Official Build) (64-bit)
installed via brew cask install eloston-chromium
Extension: chromium-web-store 0.8.1
Developer mode is enabled.

[nxtester]

Same here:
Windows 10 Professional x64
Standard build of Eloston's ungoogled-chromium 80.0.3987.163 (722274). All patches applied apart from "Safe Browser".
Installed by Chrlauncher-win64-stable-ungoogled
Extension: chromium-web-store 0.8.1
Developer mode is enabled.

[NeverDecaf]

This appears to be a problem with ungoogled chromium, see the issue linked above. You can either use a build from woolyss' site or use the "load unpacked" workaround.

[Morpheus0x]

Restarting the browser fixed that for me. Using ungoogled-chromium 84.0.4147.135