Bug #117678 MySQL 8.4.2 MY-013935 IO-layer timeout before wait_timeout was reached.

• Submitted: 12 Mar 9:51
• Modified: 12 Mar 14:32
• Reporter: Pavol S
• Status: Duplicate
• Category: MySQL Server
• Severity: S3 (Non-critical)
• Version: 8.4.2
• OS: Windows
• Assigned to: MySQL Verification Team
• CPU Architecture: Any

[12 Mar 9:51] Pavol S

Description:
we used MySQL 5.7.35 + java 17 web application with connector mysql-connector-j-8.2.0.

Application is on different host and running on Windows platform. Database is running on Windows as well.

We have migrated MySQL from 5.7.35 to 8.4.2 recently with connector mysql-connector-j-9.0.0. From that time, we can see a lot of errors in MySQL log:

[ERROR] [MY-013935] [Server] IO-layer timeout before wait_timeout was reached.

The message appears many times during day with no related application logs. Has anyone experience with this? What exactly that error mean?

How to repeat:
It's occurring many times daily, without known replicable steps - it looks like random. Sometimes it's many times per hour and another 2 days nothing.

2025-03-07T06:38:22.428795Z 103 [ERROR] [MY-013935] [Server] IO-layer timeout before wait_timeout was reached.
2025-03-07T06:38:24.871810Z 77 [ERROR] [MY-013935] [Server] IO-layer timeout before wait_timeout was reached.
2025-03-07T06:38:25.664827Z 85 [ERROR] [MY-013935] [Server] IO-layer timeout before wait_timeout was reached.
2025-03-07T06:38:31.224804Z 82 [ERROR] [MY-013935] [Server] IO-layer timeout before wait_timeout was reached.
2025-03-07T06:38:49.096779Z 260 [ERROR] [MY-013935] [Server] IO-layer timeout before wait_timeout was reached.

[12 Mar 14:32] MySQL Verification Team

Duplicate of Bug #117657

[12 Mar 14:34] MySQL Verification Team

Hi,

As explained in Bug #117657 this is just an informational message that the connection dropped before it was expected to timeout from wait_timeout.

Maybe you are on bad connection, behind a NAT, on some terrible VM infrastructure (I have seen this a lot on AZURE), or you do not close connections at all.

Check out the suggested fix in Bug #117657 (lower tcp_keepalive_time)

Thanks for using MySQL