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Description

This error occurs when you attempt to assign an inappropriate or invalid value to a MariaDB system variable or a user-defined variable. It typically signifies a data type mismatch, an out-of-range value, or an unsupported option for the specified variable. This prevents the variable from being set, leading to the failure of the operation.

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Error Message

Variable '%s' can't be set to the value of '%s'

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Known Causes

3 known causes

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Incorrect Data Type Assignment

Attempting to assign a value whose data type is incompatible with the variable's expected type, such as providing a string for an integer variable.

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Value Outside Permitted Range

Supplying a numeric value that falls outside the defined minimum or maximum limits for the variable, or an invalid boolean value (e.g., 3 for a boolean).

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Invalid Option or Format

Providing a value that is not among the allowed options for an enumerated variable, or does not adhere to the required format (e.g., an incorrect date/time string).

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Solutions

4 solutions available

1. Verify Variable Name and Scope easy

Ensure you are using the correct variable name and that it's settable in the current context.

1

Double-check the spelling and case of the variable name you are trying to set. Variable names are case-sensitive in some contexts.

SET SESSION my_variable = 'some_value';

2

Consult the MariaDB documentation for the specific variable you are trying to set. Some variables are read-only or only settable at the global level (using `GLOBAL` or `SYSTEM`) or session level (using `SESSION`).

SHOW VARIABLES LIKE '%variable_name%';

3

If the variable is intended for session-specific settings, use `SET SESSION`. If it's for all connections from this server instance, use `SET GLOBAL` or `SET SYSTEM` (synonym for `GLOBAL`).

SET GLOBAL innodb_buffer_pool_size = 1073741824; -- Example for a global variable

2. Validate the Assigned Value Type and Format easy

Confirm that the value you are assigning matches the expected data type and format for the variable.

1

Examine the variable's expected value type. For example, numerical variables expect numbers, boolean variables expect `ON`/`OFF` or `1`/`0`, and string variables expect quoted strings.

SET GLOBAL max_connections = 200; -- Correct for a numerical variable

2

Ensure string values are properly quoted. Single quotes (') are generally preferred for SQL strings.

SET SESSION sql_mode = 'STRICT_TRANS_TABLES,NO_ENGINE_SUBSTITUTION'; -- Correct for a string variable

3

For boolean-like variables (e.g., `innodb_flush_log_at_trx_commit`), use `0`, `1`, or `2` (or `OFF`, `ON` for some).

SET GLOBAL innodb_flush_log_at_trx_commit = 1;

4

If you are assigning a value from another variable or a query result, ensure the type compatibility.

SET SESSION my_custom_var = (SELECT COUNT(*) FROM my_table);

3. Check for Variable Permissions and Configuration Restrictions medium

Ensure your user has the necessary privileges to set the variable and that no configuration files are preventing the change.

1

Determine if the variable requires specific privileges to modify. Some system variables are restricted to users with `SUPER` or `SYSTEM_VARIABLES_ADMIN` privileges.

SHOW GRANTS FOR CURRENT_USER();

2

Review your `my.cnf` or `my.ini` configuration file. There might be settings that restrict the modification of certain variables or define default values that conflict with your assignment.

sudo grep 'variable_name' /etc/my.cnf /etc/mysql/my.cnf /etc/mysql/mariadb.conf.d/*

3

If you encounter a permission issue, you may need to connect as a user with higher privileges or have your database administrator adjust the user's grants.

GRANT SYSTEM_VARIABLES_ADMIN ON *.* TO 'your_user'@'localhost';
FLUSH PRIVILEGES;

4. Restart MariaDB Service After Configuration Changes easy

Apply persistent configuration changes by restarting the MariaDB service.

1

If you have modified the MariaDB configuration file (`my.cnf` or `my.ini`) to set a variable persistently, you need to restart the MariaDB service for these changes to take effect.

sudo systemctl restart mariadb

2

Alternatively, you can use the `service` command on older systems.

sudo service mysql restart

3

After restarting, reconnect to MariaDB and verify the variable's value using `SHOW VARIABLES`.

SHOW VARIABLES LIKE 'variable_name';

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Related Errors

5 related errors

MariaDB Error 1231: Invalid Variable Value Assignment