NWDS ESR has a nice way to generate mapping documentation in the Spreadsheet format. Unfortunately sometimes when you double-click to see Message Mapping Overview and nothing happens. No error on UI, no error on NWDS logs under .metadata/log, or console!
If you encounter this error. You should open the relevant Message Mapping with the old swing tools and modify the MM.
Double click for mapping overview:
Or right-click and Export:
Here is the “Error” screen:
There can be several reasons for this error. There is only one question on SAP Community. There are two SAP Notes related to the problem:
2345470 – Export to Spreadsheet option for message mappings with UDF in NWDS ESR throws null pointer exception
“Export to Spreadsheet option for message mappings with UDF having resultlist argument in the signature throws null pointer exception”
This is fixed by a software update.
2480283 – NWDS error: Another key for this value already exists.
“You are using Process Integration (PI) or Process Orchestration (PO) and cannot open a mapping-object in the NetWeaver Developer Studio (NWDS) or export the mapping to spreadsheet.”
“This issue is thrown because of a duplicate variable name i.e. more than one variable having the same name.
In NWDS, from a usability point of view, this is restricted.”
The real problem in this scenario is that there are no error popup or error logs in the NWDS log directory. It makes it harder to search for the problem.
I will add 2 solutions to this problem:
1- The first suspect is variables that are not directly under the root object. For one case this was the problem.
If you want to find the variables easily, you can use the text preview. Copy the text to your favorite text editor and search for ‘*’
You can then use the search tool on the target side to find the variable.
But in some situations, the export function works properly even there is such a variable!
2- The second solution is to check RFC lookups. For another mapping, the issue was related to an RFC Lookup object. I have deleted and recreated the relevant mapping part.
We have checked nearly everything. Other than the unrelated SAP Notes, we didn’t have a clear answer to this question.
Overall, SAP should improve this situation. At least, NWDS should show/log the cause of the rendering problem with the Message Mapping.