If you have an XML-file that contains characters that are "invalid code sequences" and/or "invalid codepoints" it is the producing applications responsibility to not produce these and should be fixed.
RFC 3629 states "Implementations of the decoding algorithm MUST protect against decoding invalid sequences."
However you might be able to employ some special software to try to fix this before you try to process it in Qlik Sense.
The Unix/Linux command-line utility iconv is able to do exactly that. There are versions for Windows too of this program that you can download. https://dbaportal.eu/2012/10/24/iconv-for-windows/
Example on how to use iconv to clean a utf-8 file:
iconv -f utf-8 -t utf-8 -c file.txt
will clean up your UTF-8 file, skipping all the invalid characters.
-f is the source format -t the target format -c skips any invalid sequence
snipped from here: linux - How to remove non UTF-8 characters from text file - Stack Overflow
thank you for your really quick answer. The information is good and helps.
So in fact I now see these posibilities:
1) create correct XML (at the moment we us the XMLSerializer in C#)
2) regulary correct the XML with iconv (as a service)
3) try to find a solution within Qlik (which is not the correct way)
I will work on 1 and 2.
But isn´t there also a posibility only to load correct file entrys and skip or correct invalid content within Qlik?
Sorry for this last attempt...