Error 46: UNKNOWN_FUNCTION

Tip

This error occurs when ClickHouse encounters a function name that it does not recognize or that is not available in the current context. It typically indicates a typo in the function name, a missing user-defined function (UDF), or use of a function that doesn't exist in your ClickHouse version.

Most common causes

1. Typo in function name

   • Misspelled function name
   • Incorrect capitalization (though ClickHouse is usually case-insensitive for function names)
   • Extra or missing characters in function name

2. User-defined function not properly configured

   • Python or executable UDF not uploaded or registered correctly
   • UDF configuration XML not loaded properly
   • UDF script execution permissions issues
   • UDF dependencies or libraries not available

3. Function not available in current ClickHouse version

   • Functions introduced in later versions than the one you are using
   • Experimental functions not enabled

4. Function exists but identifier is confused

   • Column name confused with function name
   • Similar-named function exists (error may suggest alternatives)
   • Identifier scope issues