Several PC Cannot Connect To MySQL Server on Certain Time I have a network of 10 PCs and 1 Server. I installed MySQL Community Server v5.6.10 64-bit on the Server, and all the PCs are Windows XP, using ODBC Connection 5.2(a).

Some of the PC (previously it was 3, now become 4) cannot connect to the MySQL at a certain time, which is 2.00 pm. Before, it was OK, the client can connect to the Server normally, but at 2.00 pm, those PC cannot connect anymore, with this error:

Your connection attempt failed for user xxx@xxx from your host to server at 
xxx.xxx.xxx.xxx:xxxx. Cannot connect to MySQL Server on xxx.xxx.xxx.xxx (10055)
Please:
1. Check that mysql is running on server xxx.xxx.xxx.xxx
2. Check that mysql is running on port xxxx
3. Check the xxxxxx has rights to connect to xxx.xxx.xxx.xxx from your address (mysql rights define what clients can connect to the server and from which machines)
4. Make sure you are both providing a password if needed and using the correct password for xxx.xxx.xxx.xxx connection from the host address you're connecting from


From the above error message:


I already check that mysql is running (other PC can access it normally)
I also check MySQL to run in port xxxx
I also check the user xxxxxx has rights to connect (because it can connect to the server before 2 pm)
I also check the password has been provided correctly
I also check the maximum number of connection in my.ini, which I set to 0 (unlimited connection)
I also check the network connection, but find no problem since I can still ping the server and other PC


The only action I do to make everything work again is by restarting the PC (client), however, I don't want such solution. I want to know what's the cause, is it because of the ODBC connector, the PC, or any other reason. Could anyone give me some hints on what I should check?

Thank you
This has nothing to do with the MySQL server, so no troubleshooting on that side should be needed.  It is also unrelated to usernames, machine names, and passwords.   

C:\&gt;perror 10055
Win32 error code 10055: An operation on a socket could not be performed because
the system lacked sufficient buffer space or because a queue was full.


The MySQL server is not returning this error.  Windows, on the client side, is generating this error locally, when you're trying to connect, because of a resource shortage on the client system.  Of course, a reboot of the client would clear this right up... until you hit the limit again.

The most likely cause of this would be that you have an application running on those same machines is not releasing system resources properly... It wouldn't necessarily even have to be the application that's accessing MySQL but that's probably a good bet if that's the only application where you're experiencing problems.

This command, run on the client that is experiencing the problems, will list all of your currently open network sockets, as well as the name of the application that owns them:

C:\netstat -a -b -n 


Running this on a machine that is unable to connect should give you an idea of which application is causing the problem because you will likely see an inordinate amount of sockets owned by one application.

The Windows error is also known as WSAENOBUFS.