Recently, I received numerous queries from users who encountered an error when attempting to open a PST file. The error message they encountered was ".pst is not Compatible." Errors of this nature can pose a significant risk to the integrity and security of your PST file. Such issues warrant serious attention and should be addressed with the utmost care. Consequently, I've authored this blog to provide a solution to this problem for our users.

Causes for the error ".pst is not Compatible"

The error ".pst is not Compatible" arises when an attempt is made to open a PST file created in the UNICODE format using an ANSI format email client version. It typically occurs when a user creates a PST file with a newer version of Outlook, such as Outlook 2003, and then tries to open it with an older version, such as Outlook 2002 or earlier. This error indicates that the PST file being accessed is incompatible due to a format mismatch.

How to fix error ".pst is not Compatible"

As we've discussed, the 'PST not compatible' error arises when attempting to open a UNICODE PST file with an older Outlook version that uses the ANSI format. To resolve this error, the solution is straightforward. You'll need to create an ANSI format PST file first. After creating this file, you can import all the essential data from the original PST file into this newly created PST. Once this process is complete, you can open the file without encountering any errors. Let's delve into the steps for accomplishing this:

  1. Start with any version of Outlook from 2003 to 2016, let’s say 2010 and run it in your system.
  2. Once the program is running well, look for the File tab and click on it.
  3. Now, in the File’s menu, look for the Info option and select Account Settings option from there.
  4. As you do that, an Account Settings window will open and there you need to select the Data File option.
  5. In the toolbar section of Data File click on the Add button.
  6. Now, as the next important step of creating a file, you provide a name to the file.
  7. From the Save as type drop-down box select Outlook 97-2002 Data File as the saving option and click on OK to proceed.
  8. Now, when prompt, click on Yes to create in ANSI format.
  9. Finally, click on Close to finish it.
  10. Now, you will be back in the Outlook Navigation pane, there you can easily find the PST file you have just created. So, now it is the time to transfer all the data from the original PST.
  11. To transfer all the contents and items of the original PST to the newly created PST, all you need to do is drag and drop.

By following the steps outlined above, you'll successfully open the newly created ANSI format file with the older version of Outlook. This method is effective, free, and straightforward to grasp. However, it can also be somewhat labor-intensive. You'll need to manually drag and drop each individual item from the original file to the new one, which can be a time-consuming and tiring process. If you find this approach cumbersome, you can opt for an alternative method by utilizing Outlook's Import and Export utility to streamline the process.

If you are unable to carry out the actions mentioned above or continue to encounter the error, it suggests that your PST file may be corrupted. In such a scenario, repairing the corruption is necessary. PST files can become corrupted for various reasons, and there are limited methods to address the issue. Therefore, we recommend utilizing Kernel for Outlook PST Repair software for this purpose. This tool excels at repairing severely corrupt PST files quickly and enables you to save them to a preferred location. Notably, this tool has no size or file quantity limitations and maintains the original quality of the file during the repair process.


In this blog, we have addressed the issue where users encounter the error ".pst is not Compatible" while attempting to open a PST file. We identified that this error results from a format mismatch between UNICODE and ANSI. To resolve it, we demonstrated the process of using Outlook 2010 to create a new ANSI format PST and then migrating all items from the original PST to the new one. However, if the error persists, it signifies PST file corruption, and we recommended using the Kernel for Outlook PST tool to resolve PST corruptions and ultimately eliminate the error.