Service error supplier

Summary:

Supplier is trying to register itself but it gets stuck due to an error

Content (please ensure you mask any confidential information):

In the categories selection section the supplier receives this error which does not make sense, after selecting the category

What can this be? it has happened with two suppliers during the last week and start of this week

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):