How to fix loading of Information Service Pstprx.dll

As an administrator you are often called upon to upgrade Office and other Microsoft products for your end users. You also know that getting error messages are part of the process and that very few upgrades are smooth.

One of the error messages you may receive, after upgrading Office XP, is an error message indicating that MAPI was unable to load the information service Pstprx.dll.

This can happen if you were upgrading and you were also using Microsoft Outlook in Internet Mail Only (IMO) mode. If you remove Office XP and then revert back to Microsoft Office and then try your upgrade again you might receive a MAPI error message when you attempt to restart Outlook. Oftentimes this happened with upgrades involving Microsoft Office 2000, Outlook 2000 and Outlook 2002.

The error message says that Outlook can’t open your default email folders and that it cannot find the .dll file for the information service. Hence, MAPI is unable to load the Pstprx.dll information service.

Depending on who you were upgrading the filename for, Pstprx.dll may be either Pstprx.dll or Pstprx32.dll. Upgrades over Outlook 2000 while in corporate or workgroup (CW) mode result in an error message referencing the filename Pstprx.dll. Upgrades over Outlook 2000 in IMO mode result in an error message referencing the filename Pstprx32.dll.

You are getting this error because of the profile that is being used is not the one intended for the upgrade. During the upgrade, the profile gets upgraded and a registry key is set that will not allow the profile to be upgraded again. If you later revert back to Outlook 2000 IMO and choose the current profile as the one to use then that profile will be skipped during the next upgrade process. So you end up with profiles out of sync.

Getting the latest service pack can fix this problem. But if you need a workaround then you have a couple options. Your first option is to manually change the profile. Your second option is to manually create a new profile.

If you want to change the profile:

  • Start by first closing Outlook
  • Select the Start button and bring up Settings
  • Click on the Control Panel icon and then double-click on Mail
  • Select Show Profiles which will bring up a box showing the existing profiles set up on the computer. Make sure that the profile you need is listed. If Outlook is using the Microsoft Outlook Internet Settings profile then you should select the second profile as the first one is most likely damaged
  • Click Always use this profile, and then click on the second profile that is shown
  • Hit enter or click the OK button.

The second option you have is to create a new mail profile.

  • Go to the control panel
  • Double-click Mail, show profiles and then click Add and name your new profile
  • Click OK or hit enter. You might also want to remove all the profiles that are listed – that you don’t need – before adding a new profile just to ensure you are starting with a clean slate. Also, add a new email account and fill in the necessary information
  • Click Finish and select the profile that you just created if the Always use this profile box is selected. If you skipped adding a new email account then the next time you reopen Outlook it will prompt you to create a new Mail Profile.

It’s possible that you may also have to click the Prompt for Profile option after you’ve created a new profile.

This procedure should solve your problem. If it doesn’t solve your problem then you should check your registry key to see if it is correct.

Hit Start, run and then type in regedit. Look for the following registry key: Hkey_local_machine/software/micrososft_office/9.0/outlook/setup

Next, right click on mailsupport to verify that is shows internetmail-0 or workgroup 1.

Do not change any of the registry keys unless you are certain of your changes. And always backup your registry before making any changes.

Another situation can occur that can cause you to get the error message ‘MAPI was unable to load the information service PSTPRX.DLL’ and that is when Outlook is not specified as your default mail client.

If this happens you can fix this problem by running the Fixmapi.exe utility program. Close Outlook and any other email related programs. Hit the Start button and select Run. You can try typing in Fixmapi.exe. You might need to first find it using the Browser button. After you have found its location you can then execute it by simply double-clicking on it.

Written by Mike Rede

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