Trying to send the portal invitation to a customer and this error populates:
This is related to the Work 365 app user not having the correct permissions assigned. 
Go to CRM > Advanced Settings > Security > Users > Work 365 > Select the user that has this ID: e4b1a995-abe3-4350-a61c-65fccd32e8bd

Select the user and click Manage Roles. Ensure only the following security roles are assigned:

  • Work 365 Portal Service
  • Work 365 Service


For reference: Work 365 Security Roles (