We were never able to tell for sure but had a suspicion it was caused by strange text/characters appearing in long text fields - and displaying those fields in the application. (Painful) workaround was to try cleaning up the offending field in the load, using a long series of PurgeChar statements against the field in question, specifying various ASCII codes for text to be identified and removed. We took the approach that, if a character was not part of a normal Windows keyboard, it was unnecessary and eligible for removal. This seemed to resolve the issue and got rid of the error.
I ran into the same trouble when trying to read QlikView Distribution log xml files. Looks like there is no override for this in QlikView or Qlik Sense, but there is an workaround by editing the xml file, manually or automaticly using 3rd party software.
