I was trying to open a users saved internet calendar in Outlook 2007 and wasn’t able to do it, I kept getting prompted that the file wasn’t allowed. Now I knew that Outlook 2007 is capable of opening the file (.ics) and that they had the file in their Outlook 2007 prior to reinstalling the software. I kept getting errors from Outlook 2007 saying that it couldn’t open the file and it took me forever to find the right place to fix this issue. In this guide I will explain a little more about the errors I was getting and how to solve the problem by a simple registry edit.
You might run into the error (.ics isn’t a valid internet calendar file) or some other iteration of the error and Outlook won’t allow you to import the (.ics) file. I searched everywhere for a solution and some pointed to a corrupt installation of Outlook 2007 or the entire Office 2007 suite. I searched the registry and found that a simple change to one key can fix this common problem, getting errors with (.ics) extensions.
Looking around on the internet a few other solutions that didn’t work for me but others might want to try:
Reinstall Outlook or Entire Office 2007 Suite (takes some times but some people claim this fixed the problem)
Open the (.ics) file in notepad and remove any reference to BYDAY (mine didn’t have this at all)
Make sure you don’t have 2003 and 2007 installed at the same time (I didn’t but some users reported this as the cause of the problem so make sure your old version is gone off the system just to be safe)
So now let’s fix the problem the way that worked for me, just follow these steps:
Type regedit (in search bar or if XP click Run and type regedit)
Navigate to this key HKEY_CURRENT_USERSoftwarePoliciesMicrosoftOffice12.0OutlookOptionsWebCal
Double-Click DWORD labeled Disable (in right hand view pane)
Change value to 0 (the number zero)
Close the registry
Close Outlook 2007 (if open)
Click Import and Export
Click “Import an iCalendar (.ics) or vCalendar file (.vcs)”
Browse to your .ics file and select it.
Your Calendar should show up as a new calendar
That is all there is to it, you simply have to set Outlook settings to allow internet calendars before you can open the file. If the value listed above is a 1 then the internet calendars are disabled and that is why you get the message saying it’s an invalid file. Well I hope this fixes your issues with importing (.ics) files.