You clicked a notifier for an invitation to a workspace, and then clicked Accept in the Respond to Invitation window. You have received an Invitation Requires Update message informing you that you cannot accept invitations from earlier versions of SharePoint Workspace.
The inviter sent you an invitation to a workspace that was created in an earlier version of SharePoint Workspace, but security settings in your account currently only allow you to accept invitations to workspaces created in the current version.
Depending on management policies applied to your account, you may be able to change this security setting and then accept an invitation to this workspace (and other workspaces created in an earlier version of SharePoint Workspace).
Changing the workspace version security setting
On the File tab, click Info, click Manage Account, and then click Account Preferences.
Click the Security tab.
Under Workspace Restrictions, uncheck Restore or join only Microsoft Office Groove 2007 (or later) workspaces.
If this setting is grayed, then you cannot change it according to management policies. See your administrator for more information.
If you changed this setting successfully and now want to accept the invitation, you can redisplay it in your Message History: On the File tab, click Info, click Messages and Contacts, and then click Message History.