Notice: Upcoming version 1.4.0 will no longer support import of Excel files, at least not out of the box.
Why?
Thirty bees uses third party library to read excel files. Currently used library is no longer maintained, and does not run properly on all supported version of PHP (specifically on PHP8). There are alternative libraries that we could use, but those does not run on older supported php versions (php 7.0 and php 7.1).
Because there is not a library that we could use that supports all php versions thirty bees support, we had to remove excel import functionality from the core (together with current library).
But don't worry. Import functionality was extended, and we have introduced ability to register custom importer via module. And we will release new module 'Excel Import Datasource' shortly.
You will be able to install this module if you run on on PHP 7.2 and newer. With this module installed, the Excel import will be allowed.
This extension also allows for different data source implementation, for example import from XML files, or from API.
If you are running on php 7.0 or 7.1 -- you should consider updating your PHP version.