Magnolia 5.6 reached end of life on June 25, 2020. This branch is no longer supported, see End-of-life policy.
...
Our default configuration is not using the server mode and therefore if one tries to initiate a backup call via CLI or REST, it will be failing due to the fact that H2 doesn't allow more than one connection at a time. We didn't have this issue in Magnolia before but for some reason (most likely due to H2 or Jackrabbit updates) we experience it now. A temporary workaround is to make H2 run in the server mode, by removing removing DB_CLOSE_ON_EXIT=FALSE
and adding from the value of the url
parameters and adding AUTO_SERVER=TRUE
to the value of the url
parameters:
<param name="url" value="jdbc:h2:${wsp.home}/db;AUTO_SERVER=TRUE" />
...