Here the scenario, you have a SharePoint Meeting Workspace. Near the top left of the page you will see a Go to Calendar link. You click the link and get a 404 error.
What this typically means is that there was a calendar that used to exist that does NOT exist anymore, the location has changed, or in general the url has been changed in some way.
Your first step is to figure out if the calendar that it is looking for still exists or not. You can look at the url that the Go to Calendar link points to, you will see that the name of the calendar (most likely) as the last item in the url. It may have %20 where there were spaces in the name.
Look on the Site Hierarchy on the left of the page. Look through the list of items for something that might be a matching calendar to the one you are looking for.
If the calendar no longer exists, create a new calendar with the same url as the one that the Go to Calendar link points to. The link should now work if you named it the same.
If the link does not work the url is somehow different. In this case, you can try to correct the url difference recreating the site in a different path that will make the url correct.
Also, you don’t mind making it so officially Microsoft won’t support you, you can always do a search and replace in the content database. The SQL statement would look something like this:
set [nvarchar4] = '/myoldpath/MyMeeting'
where [nvarchar4] = '/mynewpath/MyMeeting''
Please note that if you have delete an event a calendar you will need to create a new event and re-link the event to a workspace. You can do that by following the instruction here and then scroll to the “Create or link to a Meeting Workspace site when you create an event. “