I am also getting the exact same error and just found this post to see if anyone else it having the same issue.
Here are some screenshots to show the steps I took to reproduce my error. As you know when trying to add a microservice solution to abp suite you can't add the root solution.
I followed the instructions and added the administration project from the services folder.
As you can see there is an option to replace theme packages with source code.
So is this a bug that should not be allowed? I haven't found any documentation for customizing the Lepton Theme with the microservices template? Should I be downloading the source code to a seperate root folder and adding the style.css to the custom.css file as stated in the documentation?
