Maximum string length (&1 bytes) exceeded

What causes this issue?

The current statement attempted to modify an ABAP string in such a way
that the maximum string length of &V1& is exceeded.
This situation can occur in all statements that make strings longer
(such as CONCATENATE, REPLACE, or SHIFT LEFT), plus in string ex
pressions and in CALL TRANSFORMATION.

How to fix this error?

Once the exception CX_SY_STRING_SIZE_TOO_LARGE is caught, the content of
the target string is undefined. The target string may already be
modified in parts and have reached this size. For this reason it should
be initialized once the exception is caught.

Error message extract from SAP system. Copyright SAP SE.