As part of app publishing process on Microsoft AppSource, we were trying to add licensing information to a solution by following this guide Appendix: Add licensing information to your solution – Power Apps | Microsoft Docs. When attempting to run the command pac solution add-license, I got the following error:

Sorry, the app encountered a non-recoverable error and will need to terminate. The exception details have been captured and will be forwarded to the development team if telemetry has been enabled. Exception Id:29c1bb96-a9fd-47a5-80fc-b6dc511b131e

Further investigation revealed that that was because of the pac version 1.9.9 is not supporting the add-license command.

So the solution is:

pac install 1.7.4

pac use 1.7.4

then execute add-license commands

Doing this fixed the issue and we were able to publish. Hopefully, this will help you when doing the app publishing with license management feature.