"Could not execute user-defined function" is a generalized error message which requires additional investigation to obtain greater insight into the root issue.
Since the error arose during import of a dataset (ie: dataset creation), the first critical question is whether or not an import UDF was involved. The default behavior for import is without a UDF; however if you did specify a UDF during the creation, that will be an very important detail to focus upon.
If there is an import UDF involved, there is a good chance that the error arises from within the UDF logic or implementation. There are several UDF-related articles in Xcalar Discourse which you may wish to view.
In particular this article on integration of Xcalar Logging may be of particular help.
If, on the other hand, no import UDF is involved, then the next step is for a Xcalar administrator to gather information from Xcalar internal log entries through Monitor:Setup by momentarily starting and stopping monitor streaming, like this:
Often the scrollable log window will have been populated with information which can be copied-and-pasted externally.
Here is an example:
Once some evidence had been spotted in the log, it's wise to copy-and-paste for safe keeping, then contact Xcalar Technical Support.
These sorts of errors will often need Xcalar Support's involvement to understand and resolve.