Error
Error Code:
1121
MySQL Error 1121: Null Value in Index
Description
This error occurs when MySQL attempts to create or modify an index on a column that is defined to allow NULL values, but the specific table handler (storage engine) or the type of index being created does not support NULLs for that index. It signals a conflict between the column's NULLability setting and the indexing constraints.
Error Message
Table handler doesn't support NULL in given index. Please change column '%s' to be NOT NULL or use another handler
Known Causes
3 known causesPrimary Key on Nullable Column
Attempting to define a PRIMARY KEY on a column that is configured to permit NULL values, which is fundamentally disallowed by MySQL.
Incompatible Storage Engine/Index
The chosen storage engine (table handler) or the specific type of index being created does not support including NULL values in the indexed column.
Unique Index on Nullable Column
Defining a unique index on a column that allows NULLs, where the underlying handler or specific index configuration prohibits NULLs within that index.
Solutions
Coming SoonDetailed step-by-step solutions for this error are being prepared. In the meantime, try these general troubleshooting tips:
General Troubleshooting Tips
- Check the error message carefully for specific details
- Review recent changes that might have caused the error
- Search for the exact error code in the official documentation
- Check log files for additional context
- Try restarting the application or service