Key figure block &1, row &2, column &3: Formula cannot be converted

What causes this issue?

Beginning with Release 3.0C, the syntax of various formula types in the
Report Writer has been standardized (->
<DS:TX.RG-RW-FORMULA_SYNTAX>Syntax</>). In particular, operands in key
figure blocks are now enclosed in apostrophes ('). During the
automatic conversion to this new format, very long formulas may no
longer fit in the provided database field. This is what happened to the
formula in question in row &v2&, column &v3& of the key figure block
no. &v1&.

System Response

Since an automatic correction is not possible, the formula must be
deleted. The formula is set to the value 0.
Make sure that the converted form of the formula is first stored when
the report is saved.

How to fix this error?

Edit long formulas. Unlike in previous Releases, you can now also
refer to a formula within a formula. This enables formulas to be
defined more compactly. You can also define a key figure block with
the required parts of a formula and suppress them in the report.
Make sure you read OSS Note 41938. The program described in this note
lists all of the key figure block formulas that may exceed the maximum
valid length as a result of this conversion.

Error message extract from SAP system. Copyright SAP SE.