12 Most Common MySQL Errors

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June 27, 2020
12 Most Common MySQL Errors | Aamir Ali Bangash

While utilizing MySQL there can be scarcely any situations where you would not have the option to access or use MySQL appropriately. These circumstances can be irritating, however are effectively fixable. Be that as it may, before you search for the solution, you should know the issue! Here are a portion of the common errors you may go over when utilizing MySQL.

1: Access denied

MySQL gives a benefit system that verifies the client who interfaces from a host, and connects the client with get to benefits on a database. The benefits incorporate SELECT, INSERT, UPDATE, and DELETE and can recognize unknown clients and award benefits for MySQL explicit capacities, for example, LOAD DATA INFILE and managerial tasks. The entrance denied error may happen due to numerous causes. As a rule, the issue is caused as a result of MySQL accounts that the client programs use to associate with the MySQL server with authorization from the server.

2: Lost connection to MySQL server

The lost connection to MySQL server error can happen due to one of the three likely causes clarified in this segment. One possible purpose behind the error is that the system network is problematic.

System conditions ought to be checked if this is a successive error. In the event that an error message like "Lost connection to MySQL server" shows up while questioning the database, it is sure that the error has happened due to organize connection issues.

The connection_timeout system variable characterizes the quantity of seconds that the mysqld server hangs tight for a connection parcel before connection break reaction. Inconsistently, this error may happen when a client is going after for the underlying connection to the server and the connection_timeout value is set to a couple of moments. For this situation, the issue can be settled by expanding the connection_timeout value dependent on the separation and connection speed. SHOW GLOBAL STATUS LIKE and Aborted_connects can be utilized to decide whether we are encountering this all the more habitually. It tends to be absolutely said that expanding the connection_timeout value is the solution if the error message contains perusing approval bundle. It is conceivable that the issue might be confronted in light of bigger Binary Large OBject (BLOB) values than max_allowed_packet. This can make a lost connection the MySQL server error with clients. In the event that the ER_NET_PACKET_TOO_LARGE error is watched, it affirms that the max_allowed_packet worth ought to be expanded.

3: Password fails when entered incorrectly

MySQL clients request a password when the client program is summoned with the

— password or - p

alternative without the password value. Given below is the command:

› mysql -u user_name -p
Enter password:

On a couple of systems, it might happen that the password works fine when determined in an alternative record or on the order line. Be that as it may, it doesn't work when entered intuitively on the Command Prompt at the Enter password: brief. It happens in light of the fact that the system-given library to peruse as far as possible the password values to few characters (typically eight). It is an issue with the system library and not with MySQL. As a workaround to this, change the MySQL password to a worth that is eight or less characters or store the password in the choice document.

4: Host host_name is blocked

In the event that the mysqld server gets such a large number of connection demands from the host that is interrupted in the middle, this error happens:

Host 'host_name' is blocked because of many connection errors.
Unblock with 'mysqladmin flush-hosts'

The max_connect_errors system variable decides the quantity of successive interrupted connection requests that are permitted. Once there are max_connect_errors failed requests without a fruitful connection, mysqld accept that something isn't right and obstructs the host from further connections until the FLUSH HOSTS statement or mysqladmin flush-has command is given.

mysqld obstructs a host after 100 connection errors as a default. It very well may be balanced by setting the max_connect_errors value on the server startup, as follows:

› mysqld_safe --max_connect_errors=10000

This value can likewise be set up at runtime, as follows:

mysql› SET GLOBAL max_connect_errors=10000;

It ought to be checked first that there is nothing wrong with TCP/IP connections from the host if the host_name is blocked error is gotten for a specific host. Increasing the value of the max_connect_errors variable doesn't help if the system has issues.

5: Too many connections

This error shows that all accessible connection are being used for other client connections. The max_connections is the system variable that controls the quantity of connections to the server. The default value for the greatest number of connections is 151. We can set a bigger value than 151 for the max_connections system variable to support a bigger number of connections than 151.

The mysqld server process really permits one more than (max_connections + 1) value clients to connect. The extra one connection is saved for accounts with CONNECTION_ADMIN or the SUPER privilege. The privilege can be conceded to the administrators with access to the PROCESS privilege. With this access, the administrator can connect to the server utilizing the held connection. They can execute the SHOW PROCESSLIST command to analyze the issues despite the fact that the most extreme number of client connections is exhausted.

6: Out of memory

If the mysql needs more memory to store the whole request of the query issued by the MySQL client program, the server shows the given below error:

mysql: Out of memory at line 42, 'malloc.c'
mysql: needed 8136 byte (8k), memory in use: 12481367 bytes (12189k)
ERROR 2008: MySQL client ran out of memory

So as to fix the issue, we should initially check if the query is right. Do we anticipate that the query should return such a large number of columns? If not, we should address the query and execute it once more. If the query is right and needs no adjustment, we can connect mysql with the – quick option. Utilizing the – quick option results in the mysql_use_result() C API work for getting the result set. The function includes more burden the server and less burden on the client.

7: Packet too large

The communication packet is one of the given below list:

  • A single SQL statement that the MySQL client sends to the MySQL server
  • A single column that is sent to the MySQL client from the MySQL server
  • A binary log event that is sent from a replication master server to the replication slave
  • 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.

The default max_allowed_packet size is 16 MB for the MySQL client program. The following command can be used to set a larger value:

› mysql --max_allowed_packet=32M

The default value for the MySQL server is 64 MB. It should be noted that there is no harm in setting a larger value for this system variable, as the additional memory is allocated as needed.

8: The table is full

The table-full error occurs in one of the given below conditions:

  • The disk is full
  • The table has reached the maximum size
  • The actual maximum table size in the MySQL database can be determined by the constraints imposed by the operating system on the file sizes.

9: Can’t create/write to file

This demonstrates MySQL can't make an temporary file in the brief index for the result set on the off if we get the given below error while executing a query:

Can't create/write to file 'sqla3fe_0.ism'

The solution for the error is to start the mysqld server with the – tmpdir alternative. Command given below:

› mysqld --tmpdir C:/temp

10: Commands out of sync

The commands out of sync error is received if the client functions are brought out of order. It means that the command can't be executed in the client code. For instance, if we execute mysql_use_result() and attempt to execute another query before executing mysql_free_result(), this error may happen. It might likewise occur if we execute two queries that gives the result set without calling the mysql_use_result() or mysql_store_result() functions in between.

11: Ignoring user

The given below error is received when a record in the client table is found with an invalid password upon the mysqld server startup or when the server reloads the grant tables:

Found wrong password for user 'some_user'@'some_host'; ignoring user

The record is ignored by the MySQL permission system accordingly. To fix the issue, we ought to allot another password for the record.

12: Table tbl_name doesn’t exist

The given below error demonstrates that a specified table doesn't exist in the default database:

Table 'tbl_name' doesn't exist
Can't find file: 'tbl_name' (errno: 2)

Now and again, the client might be referring to the table incorrectly. It is possible because the MySQL server utilizes files and directories for storing database tables. The database and tables names may can be case senstive depending on operating system file management.

The references to a specified table utilized inside a query must utilize a similar letter case for non case-delicate record systems, for example, Windows.

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