On recent OS distributions, two conflicting changes can bring trouble.
MariaDB refuses connections with ‘utf-8’ encoding
Recent MariaDB does not like the $conf[‘sql’][‘charset’] default value of ‘utf-8’. It runs fine if you change to the more precise ‘utf8mb4’ encoding. This is what recent MySQL understands to be ‘utf-8’. You could also use ‘utf8mb3’ but this won’t serve modern users very well. The ‘utf8m3’ value is what older MariaDB and MySQL internally used when the user told it to use ‘utf-8’. But this character set supports only a subset of unicode, missing much-used icons like ☑☐✔✈🛳🚗⚡⅀ which might be used anywhere from calendar events sent out by travel agencies to todos or notes users try to save from copy/pasted other documents.
I have changed the sample deployment code to use utf8mb4 as the predefined config value.
Shares SQL driver does not understand DB-native charsets
The Shares SQL driver does some sanitation and conversion when reading from DB or writing to DB. The conversion code does not understand DB native encodings like “utf8mb4”. I have applied a patch to the share library that would detect and fix this case but I am not satisfied with this solution. First, this issue is bound to pop up in more places and I wouldn’t like to have this code in multiple places. Either the DB abstraction library horde/db or the string conversion library in horde/util should provide a go-to solution for mapping/sanitizing charset names. Any library using the config value should know that it needs to be sanitized but should not be burdened with the details. I need to follow up on this.
Update
See https://github.com/horde/Util/commit/7019dcc71c2e56aa3a4cd66f5c81b5273b13cead for a possible generalized solution.