Conversion error in language-dependent template (see long text)

What causes this issue?

A conversion error occurred in a language-dependent HTML template.
Service and theme: &V1&
Program: &V2&
Screen: &V3&
Language: &V4&

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?

Contact the person responsible.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.