How To Fix SL166 - System log message &1&2 is not defined

SAP Error Message - Details

• Message type: E = Error

• Message class: SL - System log

• Message number: 166

• Message text: System log message &1&2 is not defined

What causes this issue?

A function refers to a system log message, which is not known to the
system.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Analyze a part of the system log and use the system log messages there,
or check using transaction <NP>SE91</> (<LS>-> Tools -> CASE ->
Development -> Program maintenance -> System log messages -> List all
numbers</>) which messages actually exist.

Error message extract from SAP system. Copyright SAP SE.