Gender '&1' is incorrect.

What causes this issue?

The employee's gender is not correct.
The system needs this data to evaluate deductions for the Pension Fund.

How to fix this error?

Correct the gender in the <ZK>Personal Data</> infotype (0002).

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

Error message extract from SAP system. Copyright SAP SE.