Cannot retrieve user rules from database

I just have deactivated NF and changed admin email. Then i have reactivated NF again and didn’t see any noctice.

NF iss very strange.

Hi,

Where did you change the admin email: From the WordPress “Users” menu, or the “Settings” Menu or from NinjaFirewall “Event Notifications” menu?

it’s in admin profile.

Maybe you (or your host) had a database backup running and the tables were locked which would explain the message? Or your DB was too slow and it was not possible to connect to it?

I can change the admin password and I don’t get any error.

No, there is no backup running or my DB is too slow.
I run 2 site on a VPS 2GB ram. Everthing are very fast.

I have tried to change email 3 times. This notice always display.

Did you check MySQL log?
The firewall will display the error message if this query failed:

SELECT * FROM '{table_prefix}options' WHERE 'option_name' = 'nfw_rules'

Where i can find MySQL log file ?

I’m using MariaDB on EasyEngine.

Depends on your OS, distro etc.
Folders:
/var/log/ and /var/log/mysql/
/var/lib/mysql/

Files: /var/log/messages

I’m installing all site on Ubuntu. I had install suhoshin on my VPS.

There is no error message in log file.
I have checked /var/log/mysql and all log files in /var/log

We can force NinjaFirewall to write the error message to the dashboard.
But fist, I need to know which message exactly you received because there are 3 differents ones.
Is it:
Cannot retrieve user rules from database (#1)
Or:
Cannot retrieve user rules from database (#2)
Or:
Cannot retrieve user rules from database (#3)

It is: Cannot retrieve user rules from database (#2)

As i remember it. ??

You can try this:

1. Download the /plugins/ninjafirewall/lib/firewall.php to your computer.
2. Make a backup of it (very important).
3. Open firewall.php and search for those 2 lines:
–Line 325:

define( 'NFW_STATUS', 7 );

–Line 331:

define( 'NFW_STATUS', 8 );

-Replace those 2 lines with that one:

define( 'NFW_STATUS', htmlspecialchars($nfw_['mysqli']->error) );

4. Save and upload the new version.
5. Go to your admin dashboard and paste here the error message.
6. Restore the original firewall.php backup script.

I do as you say, but there is no error message, and there is no notice appear.

I will restore my VPS then i can test more.

After i restored my VPS, replaced your code, changed email again.
And this is a error message:

NinjaFirewall fatal error: unknown error #MySQL server has gone away. Review your installation, your site is not protected

.

That is a MySQL error/issue.
You will need to check the doc (https://dev.mysql.com/doc/refman/5.7/en/gone-away.html) and solve the problem.
Check time out values, connection etc.