Hello @hello_knime. This bug probably occurs when you provide the anonymization conditions that are not possible to fulfil. I may suggest you to try to make your anonymization requirements a bit loose. One of the most simple way to do that is to set up the suppression limit more than 0. It means that you would allow the algorithm to produce completely anonymized records (with *-values for quasi-identifiers) for some outliers in your data set.
Also you can try to set up a wider range of hierarchy levels in case you restricted them, or maybe you should revise your hierarchies.
Please let me know if this advice is helpful for you, and if it helped to get rid of this error message.
Otherwise please provide more details about the settings that you are using, or maybe you could share a workflow.
Best regards, Artem.