This error can often be resolved by either editing the hosting username or by deleting and re-adding the hosting user: https://kb.blackbaud.com/articles/Article/40016

If recreating the user does not resolve the issue, click Chat with Support and reference this article. Please provide the analyst with the following information:

  1. Document the exact wording of the error message.
  2. The Hosting username of the affected user.
  3. List the exact steps to duplicate the issue.