When you try to install an extension from your computer (not from Chrome Web Store) by dragging and dropping it onto Chrome extensions page, you may get ‘Attempted to downgrade extension’ error, let us see how to overcome this error and install the extension anyway in Chrome.
Fixing Attempted to downgrade extension Error in Chrome
Keep a copy of extension file in another location on your computer.
1. Open Windows Explorer, click on Organize>Folder and Search Options>View remove tick mark for ‘Hide extensions for known file types’, click ‘OK’.
2. Now replace crx extension with zip, for example, here you’re changing extensionname.crx to extensionname.zip, click ‘Yes’ and extract files to a folder.
3. Now visit Chrome://extensions page, and enable ‘Developer mode’, click on ‘Load unpacked extension…’, browse and select folder to which we’ve extracted files just now, click ‘OK’.
4. Extension will be installed successfully this time without showing any error.