Ok, downloaded the .js file from github and uploaded to themes/default/js and I am able to access the Prefixes in ACP. I am able to add prefixes and assign them to a board, but if I edit a topic and assign a prefix I get this error:
count(): Parameter must be an array or an object that implements Countable
In elkarte logs I have 2 errors:
Type of error: General
Warning: count(): Parameter must be an array or an object that implements Countable
File: sources/subs/TopicPrefixTcCRUD.class.php
Line: 209
and:
Type of error: Non specificato
Notice: Undefined index: is_first_post
iindex.php?action=quotefast;quote=66659;modify;xml
File: sources/TopicPrefix.integrate.php
Line: 77
Another error: when you edit a prefix, the custom css is not saved.