You are right - I meanwhile found the error by debugging the XSL template step by step: it was not this case, but another context, where it retrieved a non-existing node.

Thank you very much!

I have an XML source that looks shortened like this <sheetData> <row r="1" spans="1:3" x14ac:dyDescent="0.2"> <c r="A1" s="4" t="s"> <v>0</v> </c> <c r="B1" s="5" t="s"> <v>1</v> </c> <c r="C1" s=&quo...

I would relocate the result window, that appears when transforming my XML, from the bottom to the right.
When I first arranged all my windows, I had it there, AFAIR, but then I closed it and since then it is bound to the bottom of the window.