Chrome Extension - Invalid Package. Details:Can't unzip the extension

This is because there a file inside the package with a Windows invalid character in name or there a corrupted file. In my case I've tried to download the CouponsHelper extension and this error was displayed too.

I downloaded the CRX file manually and opened it with 7Zip. In the folder had a file named Icon. When I try to extract using 7Zip an error occurs too.

Note on the screenshot that there an invalid char in Icon file and that it is zero sized (possibly corrupted).

Another cause of this problem (Error: could not unzip extension) might be that you include the root directory in your zip.You should zip all files in the same level of manifest.json.

Example

-yourappfolder   |_manifest.js   |_popup.html

In this case you should zip only manifest.js and popup.html, instead of zip the entire directory yourappfolder.

In other words, in your zip file you should NOT see the yourappfolder directory.

So the trick it to compress all the files within the folder not the folder itself.

NOTE: If it's saved in Google Drive (local syncing) this well mess it up too. Drive attaches little icons to folders that show up as unknown.

So remake the folder outside of Google Drive.That's what was messing mine up after the "only compress inside of folder" fix.