ITS_FUNCTION_NESTING_NOT_ALLOW is an ABAP runtime error which you may come across when using or developing within an SAP system. See below for the standard details explaining what it means and how you can avoid or fix this runtime error.
Short Dump Classification: A - ABAP Programming Error
You can view further information about a runtme error by using transaction code ST22 which will show you this and all runtime erros that have happen in your SAP system.
Also check out the Comments section below to view or add related contributions and example screen shots.
If the error occurs in a non-modfied SAP template, you might be able to
find a solution in the SAP Notes system.
If you have access to the SAP Notes system, check there first using the
following keywords:
<runtime parameter>
Template interpretation terminated, syntax error.
Call transaction SE80 and correct the syntax error. In SE80, choose
'Internet Service' and navigate to the corresponding template. Take the
service, theme and template name from the path of the template causing
the error:
<runtime parameter>.
Remember to publish the corrected template on the 'INTERNAL' site in
order to activate the change.
Description of the error:
Please see abap error for more details about the possible cause of this runtime error and how it could be avoided.
Defining functions in a function definition is not supported.
HTMLB example, error ITS_FUNCTION_NESTING_NOT_ALLOW `function funcA()`
`function funcB()` -> error, function definition `end;`
Template <runtime parameter> contains syntax errors and therefore could not be
compiled. Cause of error Nested function definition
The syntax error is in row <runtime parameter>, column <runtime parameter>
The HTMLB row with errors is:
<runtime parameter>
ITS_FUNCTION_NESTING_NOT_ALLOW - its function nesting not allow ITS_FUNCTION_FAILED - its function failed ITS_FUNCTION_ALREADY_DEFINED - its function already defined ITS_EXPRESSION_NOT_NUM - its expression not num ITS_EXPRESSION_NOT_ANUM - its expression not anum ITS_ERRMSG_EXCEPTION - its errmsg exception