Plugins could not be found in indexes

Site Operators
1

I tried to upgrade the plugins on my tutor platform, but it is giving me errors.
This is the plugins list:
NAME STATUS VERSION
indigo enabled 15.0.0
mfe enabled 15.0.5

When I do tutor plugins upgrade all, the following error appears:
Failed to upgrade ‘indigo’: plugin could not be found in indexes
Failed to upgrade ‘mfe’: plugin could not be found in indexes

Where is the problem and how to resolve it.