[2.1.4]: upgrade from SMF 2.0.18 fails if the forum is in Slovenian language and UTF-8

[gregorklaric]

Basic Information

Upgrade from SMF 2.0.18 hangs in step 6 if the forum is in Slovenian language and UTF-8.
I get this error:
Notice
: Undefined index: charset_detected in
/home3/fungifun/public_html/gobe/forum/upgrade.php
on line
3143

I think the problem is that in the upgrade script charsets are hardcoded for each language, (starting line 3083 // Figure out what charset we should be converting from... )
whereas the languages can be either in that encoding or in UTF-8 in SMF 2.0(as in my case)
See https://wiki.simplemachines.org/smf/UTF-8_Readme

The same problem might also be present in the upgrade.php for SMF 3.0.

See also https://www.simplemachines.org/community/index.php?topic=588397.0;topicseen for more details and a workaround.

Steps to reproduce

1. Have a 2.0.18 forum in slovenian language, that has been converted to UTF-8 after install
2. Upgrade to 2.1 as described in https://wiki.simplemachines.org/smf/Upgrading

Expected result

Upgrader works and upgrades the forum to 2.1.

Actual result

Upgrade is stuck in step 6 of the upgrade process.

Version/Git revision

2.1.4

Database Engine

MySQL

Database Version

5.7.23-23

PHP Version

7.4

Logs

No response

Additional Information

No response