DzUser

There is a tool in ACP to rebuild the achievements right away (see the button in the Other Settings screenshot):
 
Before rebuilding, you can change the rules so that they add only 1 point for each content they make. By default, users get 10 points for a new item they post and 5 points for each comment/reply.

It is an available option to avoid overhead on your MySQL server. Most communities will not need it 🙂 .

Not really. The setting may speed up things slightly based on the server configuration, but I found it causes problems more often than not. Personally, I suggest leaving it disabling.

Try disabling completely the template disk caching setting for now. Does that fix the issue?

Awesome!  I’m glad you got to the bottom of the issue!  Good luck with the migration. 

Just because it’s installed on the server does not mean it’s available to the virtual host. You may need to enable it in httpd.conf. 

The module can be available to some, all, or none of the sites on the server. 

That is not normal, no. That is an indication further that either the .htaccess is in the wrong spot (make sure it's in the folder you installed the software in) or something is wrong with mod_rewrite on your server.

Ah, yes. If the forum is in a folder the .htaccess above won't work (the one he posted didn't have a folder, either). It's best if you download the file again directly from the ACP.

Based on what I am seeing on your community, the .htaccess needs to be completely replaced as our software is now in a folder which is not contained in the lines present, thus it is creating a 404.

At the end, the upgrade tries to fix any wrong or missing columns/indexes in the database.
To avoid the error be sure that your tables are all InnoDB and with a DYNAMIC row format.

Check your conf_global.php file and be sure the ibf_ prefix is properly set:
<?php $INFO = array ( [...] 'sql_tbl_prefix' => 'ibf_', [...] );  

@Afrodude : No, I didn't disabled plugins and apps before upgrade. I'll try thiw way
 
@Miss_B and @Marc Stridgen Ok, I'll try tonight too.
Thanks