Note: always restart uwsgi and nginx after solr otherwise the web API process could keep dangling connections and fail to connect to the new Solr process (I don't understand exactly what happens).
Disk is full
Note: the following actions are done every night by a systemd timer (see dolos doc and eros doc)
If a server uses Docker, sometimes the disk is full because of old Docker containers and volumes. This can be cleaned like so:
docker system prune
Check that unused volumes were deleted also (otherwise try with --volumes option).
This operation requires the unix user to root, or be in the docker group (for Debian).
Website displays "Internal server error"
This message is either caused by:
Solr is down (see previous section)
wrong data (or no data at all) fetched by the UI (from the API) causing a problem rendering the page
a bug in the UI
The first thing to do is to check if the API is OK when loading the page. See section "Find errors in Web API" to do that.
Web API returns errors
The error is probably caused by a Python exception in dbnomics-api. The exception is not visible in the JSON response of the URL, but is visible in the application log on the server.