Context:
In the upgrade documentation you can find the following sentence:

To get more verbose information about the upgrade, you can adjust the logging level as it is described in the configuration documentation.

However, it's currently not possible to adjust the log level. With OPT-1540 we accidentally removed this feature. We should think about how we can include it again.

AT:

• the upgrade logging can be adjusted again
• the documentation is adjusted so that it explains how to adjust the log level for the migration