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ERROR 1129 (HY000) host is blocked | Solution

by | Apr 29, 2025

Learn how to fix MySQL Error 1129 (HY000): “Host is Blocked Because of Many Connection Errors”. Our MySQL Support team is here to assist you with any questions or concerns you may have.

ERROR 1129 (HY000) host is blocked | Solution

ERROR 1129 (HY000) host is blocked | SolutionIf you are experiencing trouble with MySQL error 1129: “Host is blocked because of many connection errors,” you can stop worrying. Our Experts are here to help you out.

This error indicates that the MySQL server has blocked a host due to an excessive number of failed connection attempts. This is a security feature designed to protect the database from unauthorized or malicious access attempts.

Why Does This Error Occur?

MySQL maintains a count of failed connection attempts from each host. If the number of these failed attempts exceeds the value of the `max_connect_errors` system variable, MySQL automatically blocks that host from making further connections.

For instance, if `max_connect_errors` is set to 10, then after 10 interrupted or unsuccessful connection requests without a successful login, the host will be blocked. This helps prevent brute-force attacks or misconfigured programs from overwhelming the server.

Furthermore, blocked hosts can only connect again after the host cache is flushed. You can learn more about managing high connection errors in our guide on MySQL too many connections fix.

Common Causes

This error is typically not a bug in MySQL itself. Instead, it’s often caused by:

  • A misconfigured client repeatedly attempting to connect with wrong credentials.
  • A script or application making rapid, frequent connection attempts without proper handling.
  • A possible brute-force attack or internal process gone rogue.

If we observe a high number of failed connection attempts in the server logs (e.g., `auth.log`), this could be a sign that our server is under attack or that an internal application is malfunctioning.

How to Diagnose the Issue

  1. First, we need to check for misbehaving processes. On Linux/BSD systems, run the following command multiple times to spot suspicious processes:
    ps axuwwCopy Code

    Look for processes we don’t recognize or that are consuming unexpected resources.

  2. Next, examine the source IP addresses of failed connection attempts. Check if they are coming from internal addresses, such as `127.0.0.1`, `192.168.x.x`, or `10.x.x.x`. Alternatively, check if they are coming from unknown external IP addresses.

    We can use these websites to look up unfamiliar IPs:

    If the connections are coming from locations where we don’t have users or systems, the server may be under attack.

  3. Furthermore, check if the failed attempts occur regularly (e.g., every 5 minutes) or in rapid bursts. Regular patterns might indicate a scheduled script with incorrect credentials.

How to Fix It

1. Flush the Host Cache

First, unblock the host by clearing MySQL’s host cache:

  • From the command line:
    mysqladmin -u root -p flush-hostsCopy Code
  • From within the MySQL shell:
    FLUSH HOSTS;Copy Code

If you’re facing issues with access or permissions while using mysqladmin, check out:

2. Increase max_connect_errors

If the block is happening due to a low threshold, consider increasing the value:

In the MySQL configuration file (`my.cnf` or `my.ini`):


[mysqld]
max_connect_errors = 10000
Copy Code

Then restart MySQL for the change to take effect.

Or, change it temporarily via SQL:

SET GLOBAL max_connect_errors = 10000;Copy Code
This setting is crucial if you’re running MySQL in a cloud environment, such as AWS RDS. You may also need to review the max_connections setting, especially if you’re dealing with high traffic. For more information, see max_connections at AWS RDS MySQL instance sizes.

3. Restart the MySQL Server

If flushing hosts doesn’t work, a server restart will also clear the host cache.

4. Fix the Root Cause

Identify and fix the client or script that’s making repeated failed connection attempts. Common solutions include:

  • Correcting wrong credentials in scripts or applications.
  • Ensuring the application uses persistent connections instead of reconnecting repeatedly.
  • Limiting external access to the database through a firewall.

MySQL’s blocking mechanism is there to protect the server, but it can disrupt connections if misconfigured software triggers it. Hence, we always need to investigate the root cause before simply unblocking a host, especially if the server is accessible from the internet.

[Need assistance with a different issue? Our team is available 24/7.]

Conclusion

In brief, our Support Experts demonstrated how to resolve MySQL Error 1129 (HY000): “Host is Blocked Because of Many Connection Errors.”

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