Sometimes there can be communication errors when connecting to MYOB AccountRight through TOE.

If you have MYOB version 2020.2 installed, and if you still try to access MYOB file of 2019.4 through the app the system fails with error message 

[Message, The Company File version is not supported.][Message, The Company File version is not supported.] 

To fix this you need to update the current MYOB file and run through the version 2020.2

When you upgrade to 2021.5 sometimes when they have MYOB AccountRight  add-ons running and it will stop the connection. check any thing and make sure it is stopped. Search for startUp Apps. And turn off add-on.