MySQL · December 20, 2023

How to Fix MySQL Error - ER_SYNC_MASTER_DISCONNECTED

How to Fix MySQL Error - ER_SYNC_MASTER_DISCONNECTED

MySQL is a popular open-source relational database management system used by many websites and applications. However, like any software, it can encounter errors that need to be resolved. One such error is ER_SYNC_MASTER_DISCONNECTED, which occurs when the connection between the master and slave servers in a MySQL replication setup is lost. In this article, we will explore the causes of this error and provide steps to fix it.

Causes of ER_SYNC_MASTER_DISCONNECTED Error

There are several reasons why the ER_SYNC_MASTER_DISCONNECTED error may occur:

  • Network Issues: The most common cause of this error is network connectivity problems between the master and slave servers. It could be due to a firewall blocking the connection, network congestion, or a faulty network cable.
  • Server Load: If the slave server is under heavy load, it may not be able to keep up with the replication process, leading to a disconnection from the master server.
  • MySQL Configuration: Incorrect configuration settings in the MySQL server can also cause this error. For example, if the slave server is not configured to connect to the correct master server, it will result in a disconnection.

Steps to Fix ER_SYNC_MASTER_DISCONNECTED Error

Here are some steps you can take to resolve the ER_SYNC_MASTER_DISCONNECTED error:

1. Check Network Connectivity

Ensure that there are no network connectivity issues between the master and slave servers. Check if there are any firewalls blocking the MySQL replication traffic and make sure the network cables are properly connected. You can also try pinging the master server from the slave server to test the network connection.

2. Monitor Server Load

If the slave server is under heavy load, consider optimizing its performance by identifying any resource-intensive processes and optimizing them. You can also consider upgrading the hardware or adding more resources to the server to handle the replication process more efficiently.

3. Verify MySQL Configuration

Double-check the MySQL configuration on the slave server to ensure it is correctly set up to connect to the master server. Verify that the replication user credentials are correct and that the server ID and replication settings match those of the master server.

4. Restart MySQL Replication

If the above steps do not resolve the issue, you can try restarting the MySQL replication process. Stop the replication on the slave server using the STOP SLAVE command and then start it again using the START SLAVE command. Monitor the replication process to see if the error persists.

5. Seek Professional Assistance

If you are still unable to fix the ER_SYNC_MASTER_DISCONNECTED error, it is recommended to seek assistance from a professional MySQL database administrator or your hosting provider. They will have the expertise to diagnose and resolve the issue.

Summary

The ER_SYNC_MASTER_DISCONNECTED error in MySQL occurs when the connection between the master and slave servers in a replication setup is lost. This can be caused by network issues, server load, or incorrect MySQL configuration. To fix this error, you should check network connectivity, monitor server load, verify MySQL configuration, restart the replication process, and seek professional assistance if needed.

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