DLO users experience problems accessing PST files within MS Outlook when DLO is backing up the PST file.

Problem

The symptoms may include one or both of the following:

1.  When in MS Outlook, attempting to access a PST file to either view content or add content to it - may produce one of the following messages:
   A. Cannot expand the folder. The set of folders can not be opened. The file C:\...\...\MyPST.pst is in use and cannot be accessed. Close any application that is using this file, and then try again.  You might need to restart your computer.

   B. Outlook cannot start because a data file to send and receive the mail cannot be found.  To ad a data file, such as a personal folder file, double-click the Mail icon in Windows Control Panel.  The file C:\...\...\MyPST.pst cannot be accessed because another workstation has modified it.  Close and then restart all mail-enabled applications.  You might need to restart your computer.

   C. Cannot display the folder.  File access is denied.  You do not have the permission required to access the file C:\...\...\MyPST.pst

   D. Cannot display the folder.  Microsoft Outlook cannot access the specified folder location.  You don't have appropriate permission to perform this operation.

2. This message may be observed in the backup History log:
Outlook is not set as your default mail application.  Incremental changes to Outlook PST files will not be backed up.
https://eventlookup.veritas.com/eventlookup/EventLookup.jhtml?EvtlD=V-139-35840-10150

Error Message

The dloclientu.log file at "Enable Verbose Logging" will have this line in it, which indicates the DLO Agent failed to read the required registry keys as noted below:

dloclientu.exe 4216: W> mapitools.cpp( 1327 ) MapiRegistryHack() - rename failed... E0140005
 

 To turn up DLO Agent logging verbosity:
1. Launch the DLO Agent GUI
2. Select Tools > Support > Enable Verbose Logging
3. Restart the DLO Agent (don't just minimize it and maximize it)

Cause

This issue can occur because the Microsoft API which the DLO Agent uses to backup PST files incrementally expects the presence of, and access to, certain registry keys.

Within this registry path:
HKLM\SOFTWARE\Clients\Mail

These two keys must exist with these values:
(Default) = Microsoft Outlook
PreFirstRun = Either there is no default mail client or the current mail client cannot fulfill the messaging request.  Please run Microsoft Outlook and set it as the default mail client.*Microsoft Office Outlook

Solution

To resolve the PST access errors in MS Outlook, the DLO Agent must be able to backup the PST files using the VSS snapshot methodology as opposed to using the alternative MAPI methodology.

1. Validate the registry on the problematic desktop machine contains (Default) and PreFirstRun and that the values are set correctly as stated above.

2. Validate the user has the needed permissions to modify both of these keys.  i.e. change 'Microsoft Outlook' to 'Microsoft Outlook TEST'  and change 'PreFirstRun' to 'PreFirstRun_TEST'.

NOTE:  Please change the keys back to their pre-altered values, once the permissions test has been run.

NOTE: Two other root-causes known to produce similar PST access problems within MS Outlook are:
     1. Delta File Transfer not enabled in the PST Backup Selection for the Profile in question.
     2. The DLO Agent bittenss does not match the bittness of MS Outlook.  For instance, 32-bit DLO Agent backing up PST files configured in 64-bit MS Outlook.