ContributionsMost RecentMost LikesSolutionsRe: App encountering validation error Hi, If the above solution is not working for you, please raise a support ticket here for further investigation - https://apisupport.myob.com/hc/en-us/requests/new?ticket_form_id=215283 Re: App encountering validation error Hi All, Apologies for the inconvenience. Please try to revoke access and then reauthenticate. Please see below articles; Revoking access How to Complete End-User Authentication with OAuth2.0 We have developers confirming that getting the MYOB user to revoke access and then reauthorizing the API key; resolves the issue. At this stage we are not sure what actually caused this issue, but identity services are going through some changes which may have caused this issue. We will find out.