Common Errors When Using MySQL Programs That sets the packet size to 32MB. The server’s default  max_allowed_packet  value is 64MB. You can increase this if the server needs to handle big queries (for example, if you are working with big  BLOB  columns). For example, to set the variable to 128MB, start the server like this: You can also use an option file to set  max_allowed_packet . For example, to set the size for the server to 128MB, add the following lines in an option file: It is safe to increase the value of this variable because the extra memory is allocated only when needed. For example,  mysqld  allocates more memory only when you issue a long query or when  mysqld  must return a large result row. The small default value of the variable is a precaution to catch incorrect packets between the client and server and also to ensure that you do not run out of memory by using large packets accidentally. You can also get strange problems with large packets if you are using large  BLOB  values but have not given  mysqld  access to enough memory to handle the query. If you suspect this is the case, try adding ulimit -d 256000  to the beginning of the  mysqld_safe  script and restarting  mysqld . If connection problems occur such as communication errors or aborted connections, use these sources of information to diagnose problems: If the  log_error_verbosity  system variable is set to 3, you might find messages like this in your error log: If a client is unable even to connect, the server increments the  Aborted_connects  status variable. Unsuccessful connection attempts can occur for the following reasons: If these kinds of things happen, it might indicate that someone is trying to break into your server! If the general query log is enabled, messages for these types of problems are logged to it. •A client attempts to access a database but has no privileges for it. •A client uses an incorrect password. •A connection packet does not contain the right information. •It takes more than  connect_timeout  seconds to obtain a connect packet. See Section 5.1.8, “Server System Variables” . •The error log. See Section 5.4.2, “The Error Log” . •The general query log. See Section 5.4.3, “The General Query Log” . •The  Aborted_ xxx  and  Connection_errors_ xxx  status variables. See Section 5.1.10, “Server Status Variables” . •The host cache, which is accessible using the Performance Schema  host_cache  table. See Section 5.1.12.3, “DNS Lookups and the Host Cache” , and Section 27.12.21.2, “The host_cache Table” . shell>  mysqld --max_allowed_packet=128M [mysqld] max_allowed_packet=128M B.3.2.9 Communication Errors and Aborted Connections 5294 [Note] Aborted connection 854 to db: ’employees’ user: ’josh’