Hi @Haiqiang He ,
Welcome to our forum!
In order to verify your issue, could you provide some related information?
What detailed version of outlook are you using? You could update to the newest version to see if there are any improvements.
Does this issue happen to all shared calendar invitations or a specific one?
To further confirm if it is relevant to the client, try to accept the invitation on the web mail to see if same error occurs.
Based on my search, I found that there are other users who have also reported the same problem, because the disclaimer was in the email. After they updated the transport rule and added an exception that if the subject line matches "You're invited to share this calendar" then to not add the disclaimer.
See: Can't open a calendar from a sharing invitation in Outlook on the web
If issue persist, please do let me know and I'll do my best on continuing to help you.
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