Nextcloud wont' create spreadsheet

I setup an online CODE server for Nextcloud 20 and replaced the built in CODE server.

Everything works for opening existing documents and creating new documents but when creating a new spreadsheet, the file is create but it won’t open in the spreadsheet app in the CODE server. The file created appears to be corrupted since the icon to identify the spreadsheet with the file isn’t created (it is grayed out). File won’t open and reports an error that it can’t connect to the CODE server.

There is a problem with the extension.

The file extension “. xslx” may be a bug,

I also made some inquiries about this issue. Get some inspiration. This problem can be solved by modifying the file “nextcloud/apps/richdocuments/lib/appinfo/ application.php”; I’ve tested it myself.

I’m able to use with ODT (when creating new ones). Waiting on the correction in the next release.