PST File Processing Failed - Troubleshooting Guide

When uploading a PST file to RedactBox, the file shows as "Failed" with the message:

Last updated 17 days ago

Problem

When uploading a PST file to RedactBox, the file shows as "Failed" with the message:

"This file could not be processed. It may be too large or corrupt."

First, check whether it really is corruption

Large PST imports now resume automatically if they stall part-way through, instead of starting again or failing outright, so a big file that is simply slow should no longer end up here. Before going through a repair cycle:

  • Give a very large file time. A multi-gigabyte PST takes a while, and the sidebar shows its progress as it works through.

  • Check whether the import was partial rather than failed. If some items came through, the file badge says so and tells you what is missing. That is a different problem from a file that could not be opened at all.

  • Talk to us before repairing an evidential file. If the PST came from an eDiscovery, Exchange or Purview export, send us the details first. Repair tools can drop items, and we would rather investigate than have you run ScanPST over something you may need to account for later.

Cause

This error typically indicates that your PST file has internal corruption. PST files use a complex B-tree index structure to store emails, folders, and attachments. When this structure becomes damaged, email extraction tools cannot read the file properly.

Common Causes of PST Corruption

  • File size exceeded limits - Older versions of Outlook had a 2GB limit for PST files

  • Unexpected shutdown - Outlook closing unexpectedly during file operations

  • Storage issues - Hard drive errors, bad sectors, or network interruptions

  • Incomplete transfers - File not fully downloaded or copied

  • Software conflicts - Antivirus or backup software interfering with Outlook

Solution

Step 1: Run Microsoft's Inbox Repair Tool (ScanPST.exe)

Microsoft includes a free repair tool with Outlook called ScanPST.exe. This tool can fix many common PST corruption issues.

Locate ScanPST.exe on your computer:

Outlook VersionDefault Location

Outlook 365/2021/2019

C:\Program Files\Microsoft Office\root\Office16\SCANPST.EXE

Outlook 2016

C:\Program Files\Microsoft Office\Office16\SCANPST.EXE

Outlook 2013

C:\Program Files\Microsoft Office\Office15\SCANPST.EXE

Outlook 2010

C:\Program Files\Microsoft Office\Office14\SCANPST.EXE

Note: If you have 32-bit Office on 64-bit Windows, check C:\Program Files (x86)\... instead.

Run the repair:

  1. Close Outlook completely (check Task Manager to ensure it's not running)

  2. Navigate to the ScanPST.exe location and double-click to run it

  3. Browse to select your corrupted PST file

  4. Click "Start" to begin scanning

  5. If errors are found, click "Repair"

  6. Repeat steps 4-5 until no more errors are found (may take several passes)

Step 2: Re-upload to RedactBox

After repairing the PST file:

  1. Delete the failed file from your RedactBox project (click the trash icon)

  2. Upload the repaired PST file again

Still Having Issues?

If ScanPST.exe doesn't resolve the problem:

  • Try a third-party repair tool - Tools like Stellar Repair for Outlook or Kernel for Outlook PST Repair can handle more severe corruption

  • Export to a new PST - Open the damaged PST in Outlook, then export emails to a new PST file

  • Contact support - Reach out to us with details about your file and we'll help investigate

Prevention Tips

To avoid PST corruption in the future:

  • Keep PST files under 10GB when possible

  • Store PST files on local drives, not network locations

  • Ensure Outlook closes properly before shutting down

  • Regularly back up important PST files

  • Consider using Outlook's OST/cached mode instead of PST files