What is this?

 The "node block tree" is the data structure found within PST files. This data structure acts like a table of contents, that tells where all of the emails and items are located within the PST file. Typically when we see errors with the "node block tree", it is due to some items being referenced in the data structure, but cannot be found within the PST file. Often times, this indicates that the PST file is corrupt or that an update / write operation using this PST was interrupted at some point.

My file is straight from Office 365, how can it be corrupt?

Simply put, we've seen a lot of bad PST files generated from Microsoft's own eDiscovery tool. Often times, these are missing a few of the items listed in the "node block tree", causing this error. We believe there's most likely a bug with their PST generation code, which makes this issue a bit more difficult for us to resolve.

How can I fix this?

Ideally, the PST file would need to be regenerated from the source. That being said, if that's not possible, we have seen a lot of success with users using Microsoft's SCANPST.exe tool.

How do I use Microsoft's SCANPST.exe tool?

Microsoft's SCANPST.exe tool is installed as a part of Microsoft Office, and the location of the tool will vary, depending on the version of Microsoft Office you are using. To begin, close Outlook and then if you are using Office 365, navigate to this file location: "C:\Program Files\Microsoft Office\root\Office16". The SCANPST.exe tool should be located in this location, as shown.

File location with SCANPST.exe selected

If you are not using Office 365 for Outlook, please visit this link to determine the location of your SCANPST.exe tool.

Once the tool is open, simply select your errored PST file with the "Browse" button and click "Start". If errors are detected, select "Repair" to begin the repair process.