manual upgrade to 5.0 & OVERLEAF fails

[Pfiffikus]

Running
bin/up
ends up in

Initiating Mongo replica set...
time="2024-05-21T09:44:01+02:00" level=warning msg="The "SHARELATEX_DATA_PATH" variable is not set. Defaulting to a blank string."
invalid spec: :/var/lib/sharelatex: empty section between colons


Specifying SHARELATEX_DATA_PATH
results in

Initiating Mongo replica set...
Rebranding from ShareLaTeX to Overleaf
The Toolkit has adopted to Overleaf brand for its variables.
Your config/overleaf.rc still has 1 variables using the previous ShareLaTeX brand.
Moving forward the 'SHARELATEX_' prefixed variables must be renamed to 'OVERLEAF_'.
You can migrate your config/overleaf.rc to use the Overleaf brand by running:
toolkit$ bin/rename-rc-vars


How to escape this dilemma?
Where to find a step-by-step description, what to do instead of an interrupted bin/upgrade?