How do I resolve the "Got an error reading communication packets" error in Amazon RDS for MySQL or Aurora MySQL-Compatible?

Short description

If server-client connections are dropped, incorrectly closed, or unsuccessful, then Amazon RDS increases the status counter for either aborted_clients or aborted_connects. The aborted_clients parameter describes the number of connections that Amazon RDS cancelled because the client died and didn't correctly close the connection. The aborted_connects parameter describes the number of failed attempts to connect to the MySQL server.

If the value of either of these parameters increases, then you receive the following error in your logs:

"[Warning] Aborted connection abc to db: 'database name' user: 'user name' host: 'host IP' (Got an error reading communication packets)".

If the value of log_error_verbosity exceeds 2, then you also receive the preceding error. The log_error_verbosity parameter specifies the verbosity to manage events that are intended for the error log.

For more information, see B.3.2.9 Communication errors and aborted connections on the MySQL website.

The following factors might cause the Error reading communications packets error:

• Client or driver incompatibility.
• Firewalls or proxies that can close any idle connections or block a connection.
• An client-server connection that's incorrectly closed and results in a higher number of sleeping connections inside RDS for MySQL.
• A client application that incorrectly terminates a connection.
  Note: MySQL forcibly closes long-running idle connections.
• Idle connections that exceed the wait_timeout or interactive_timeout thresholds.
• A client connection that exceeds the connect_timeout seconds threshold when it gets a connection packet.
• Insufficient values for parameters, such as net_write_timeout and net_read_timeout.
• An exceeded max_allowed_packet parameter value.
  Note: If the value is too small or queries require more memory than is allocated for Amazon RDS for MySQL, then you receive the preceding error.

Resolution

Check the connectivity timeout parameter values. After you identify the root cause of your issue, change the parameter value based on the issue that you identified. Then, monitor the MySQL error logs as you test the new value.

Troubleshoot your configuration

Check whether you're using the default values of the Amazon RDS parameter group. You might need to modify the default connectivity timeout value for your DB instance. For more information, see the Parameters related to connectivity timeouts section of Best practices for configuring parameters for Amazon RDS for MySQL, part 3: Parameters related to security, operational manageability, and connectivity timeout.

Set a higher value for connect_timeout to test whether the value reduces the occurrence of the Error reading communications packets error. The connect_timeout parameter defines how many seconds the MySQL server DB instance must wait before the DB instance responds with a bad handshake. For more information, see connect_timeout on the MySQL website.

You can also modify interactive_timeout and wait_timeout. For more information about these parameters, see wait_timeout or interactive_timeout on the MySQL website. Applications that use connection pooling, such as Java, must have timeouts that match the connection pool settings.

If the instance must manage large queries, large BLOB columns, or long strings, then increase the value of max_allowed_packet. If a row has more data than the max_allowed_packet value, then you receive an error. For more information, see the max_allowed_packet section of Best practices for configuring parameters for Amazon RDS for MySQL, part 3: Parameters related to security, operational manageability, and connectivity timeout. Or, see max_allowed_packet on the MySQL website. Also, increase the net_write_timeout and net_read_timeout values.

Note: You can set net_write_timeout and net_read_timeout to the same value as wait_timeout. For more information, see net_write_timeout and net_read_timeout on the MySQL website.

Make sure that the RDS for MySQL or Aurora MySQL-Compatible connections are correctly closed. Before you exit the database, call the mysql_close() function from the client application.

Advanced troubleshooting

If you still receive the Error reading communications packets error message, then take any of the following actions:

• Turn on Performance Insights to get the time frame of the SQL statements that encounter issues. For Aurora MySQL, see Turning Performance Insights on and off for Aurora.
• Turn on slow query logs on your Amazon RDS or Aurora MySQL-Compatible DB instance to log queries that run for longer than the long_query_time value.
  Note: The default long_query_time value is 10 seconds.
• Turn on Amazon Virtual Private Cloud (Amazon VPC) Flow Logs to see whether the server or client closed the connection.
• Verify that your application correctly closed the connection from MySQL.
• Run the tcpdump command from the machine that's running the client to test sample packet captures:

  sudo tcpdump -vvv --interface eth0 port 3306 -W 10 -C 100

Related information

How do I modify the values of an Amazon RDS DB parameter group?

Why did DB connections drop on my RDS DB instance?

How can I turn on logs on an Aurora Serverless cluster so I can view and download the logs?