Login to MySQL:

mysql -u your_user -p

Then run:

USE your_discuz_db; # My DB name is ultrax.
SHOW TABLE STATUS WHERE Comment LIKE '%crashed%';

In my case, I can see 3 tables crashed. The output confirms that the key Discuz tables (pre_forum_post, pre_forum_sofa, and pre_forum_thread) are badly corrupted.


Step-by-Step Recovery with myisamchk

Because myisamchk works on raw table files, MySQL must not be running:

sudo systemctl stop mysql

Step 1: Navigate to the Data Directory
MySQL table files are usually stored in:

cd /var/lib/mysql/ultrax/

Step 1: Navigate to the Data Directory

MySQL table files are usually stored in:

cd /var/lib/mysql/ultrax/

Step 2: Run myisamchk on the Crashed Tables

Try repairing the .MYI (index) and .MYD (data) files:

sudo myisamchk -r -v pre_forum_post
sudo myisamchk -r -v pre_forum_sofa
sudo myisamchk -r -v pre_forum_thread

If you get errors, try more aggressive repair:

sudo myisamchk -o -v pre_forum_post
sudo myisamchk -o -v pre_forum_sofa
sudo myisamchk -o -v pre_forum_thread

And if that still fails:

sudo myisamchk -f -v pre_forum_post
sudo myisamchk -f -v pre_forum_sofa
sudo myisamchk -f -v pre_forum_thread

The -f flag forces recovery, even if corruption is bad.

Step 3: Start MySQL Again

sudo systemctl start mysql

Step 4: Check Tables Again

Login to MySQL:

mysql -u your_user -p

Then:

USE ultrax;
CHECK TABLE pre_forum_post, pre_forum_sofa, pre_forum_thread;