how to understand “can't connect” mysql error messages?

Question

I have the following error message:

SQLSTATE[HY000] [2003] Can\'t connect to MySQL server on \'192.168.50.45\' (4)

How would I

Answer 1

Using the perror tool that comes with MySQL:

shell> perror 4
OS error code   4:  Interrupted system call

It might a bug where incorrect error is reported, in this case, it might a simple connection timeout (errno 111)