Errors or mistakes are common in any aspects, especially in development. Using MySQL or any database can't guarantee you an error-free environment.
In this article, we will discuss the structure or anatomy of MySQL errors and how to read them. We've also picked the top 10 most common MySQL errors and their description.
The anatomy of MySQL errors
Each MySQL errors consists of the following parts that identify the error:
- ERROR NUMBER is a unique number that identifies each error.
- SQLSTATE is a code which identifies SQL error conditions.
- ERROR MESSAGE describes the error in human readable format.
Here's an example MySQL error:
ERROR 1146 (42S02): Table 'test.no_such_table' doesn't exist
In this example above:
- 1146 is the ERROR NUMBER
- 42S02 is the SQLSTATE
- Table 'test.no_such_table' doesn't exist is the ERROR MESSAGE
Common MySQL Errors
Here are the lists of most common MySQL errors:
ERROR 1045 (HY000): Access denied for user 'root'@'localhost' (using password: YES)
This one is probably encountered at least once by anyone using MySQL. This error can have many causes, such as wrong username and/or password, or lacks of permission to the database.
ERROR 2013: Lost connection to MySQL server during query
This error happens when the connection between your MySQL client and database server times out. Essentially, it took too long for the query to return data so the connection gets dropped.
ERROR 1040: Too many connections
This error means that all available connections are in use by other clients.
ERROR 2006 (HY000): MySQL server has gone away
The common reason for this error is that the server timed out and closed the connection. By default, the server closes the connection after 8 hours if nothing has happened.
ERROR 2008: MySQL client ran out of memory
This means that MySQL does not have enough memory to store the entire query result:
ERROR 1114 (HY000): The table is full
If a table-full error occurs, it may be that the disk is full or that the table has reached its maximum size. The effective maximum table size for MySQL databases is usually determined by operating system constraints on file sizes, not by MySQL internal limits.
ERROR: Packet too large
When a MySQL client or the mysqld server gets a packet bigger than max_allowed_packet bytes, it issues a Packet too large error and closes the connection.
A 1 GB packet size is the largest possible packet size that can be transmitted to or from the MySQL server or client. The MySQL server or client issues an ER_NET_PACKET_TOO_LARGE error and closes the connection if it receives a packet bigger than max_allowed_packet bytes.
ERROR: Communication Errors and Aborted Connections
If you find errors like the following in your error log.
010301 14:38:23 Aborted connection 854 to db: 'users' user: 'simplebackups'
This means that something of the following has happened:
- The client program did not call mysql_close() before exit.
- The client had been sleeping more than wait_timeout or interactive_timeout without doing any requests.
- The client program ended abruptly in the middle of the transfer.
ERROR: Can’t create/write to file
This indicates that MySQL is unable to create a temporary file in the temporary directory for the result set if we get the following error while executing a query.
ERROR: Commands out of sync
If you get this error in your client code, you are calling client functions in the wrong order. For example, if you are using mysql_use_result() and try to execute a new query before you have called mysql_free_result().
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