SQLSTATE[HYOOO]: General error: 9001 Max connect

The error means the max connect timeout (setting) was reached for MySQL. It could be a connection pooling/load balancing issue with your MySQL setup.

Ask yourself these questions:

• Does this happen on production during specific times (i.e. high traffic) or randomly?
• What optimization did you make that temporarily fixed it?

Common causes for this can be:

• Connection exhaustion (too many persistent connections not being released)
• Long running queries (clean these up)
• DB Engine misconfiguration (timeout settings could be too aggressive for your workload, check the config for max connection timeout and max connections)
• MySQL Server overload (check your server stats, is there high CPU/memory causing slow responsiveness)

When you have this information, you will likely have some more information on what is causing this issue and what to look into to fix it.

That SQLSTATE[HY000]: 9001 Max connect timeout error usually means MySQL is hitting connection or proxy limits.

Try increasing in my.cnf:

max_connections = 500
connect_timeout = 30
wait_timeout = 28800

Also check if ProxySQL or HAProxy is timing out — raise their connection timeout values too.

If it keeps happening, run

CHECK TABLE table_name;

Sometimes corruption or locked tables trigger this. You can use third-party tools like Stellar Repair for MySQL to repair damaged .ibd or .frm files.