Outlook Data Cyclic Redundancy Check Error

Why Does Outlook Show a Cyclic Redundancy Check Error?

Four causes come from Microsoft Q&A replies and articles:

• Disk errors break access to the file. Volunteer Moderator says in an April 2025 thread on a warning symbol on a drive that the error indicates a disk error and advises chkdsk.
• Drive hardware fails. Anonymous adds in that thread that CRC errors can come from hardware failure and advises a test with the manufacturer tools.
• OneDrive syncs the PST file. Moderator explains in a January 2026 thread on PST files in OneDrive that OneDrive syncs the file while Outlook expects uninterrupted exclusive use and the clash corrupts the PST file.
• PST damage causes it. Microsoft's article on the Inbox Repair tool gives the Inbox Repair tool steps for a damaged file.

Which Method Suits Your Drive?

Match your drive to a row:

5 Ways to Fix Outlook Data Cyclic Redundancy Check Error

Four remedies use Windows and Outlook tools. Method 5 adds software:

Method #1: Check the Drive With Chkdsk (Free)

Volunteer Moderator advised chkdsk for the disk error and Anonymous gave the accepted chkdsk answer in a 2012 thread on error 0x80070017. Copy the important files first because the scan can fail on a weak disk. Seven steps follow:

1. Close Outlook.
2. Search for Command Prompt and select Run as administrator.
3. Type chkdsk F: /f and press Enter. Replace F with the drive letter of the PST file.
4. Press Y when Windows asks to check the disk at the next restart.
5. Close all applications and restart the computer.
6. Wait for the disk check to finish.
7. Open Outlook and test the PST file.

Note: The 2012 thread concerns a Windows backup error and not Outlook. Both errors share the CRC message.

Method #2: Move the Data File Onto a Local Disk (Free)

Moderator describes a local copy for PST files that sit in OneDrive. Moving a file off an external drive uses the same idea when the drive responds. Seven steps follow:

1. Close Outlook and pause OneDrive when the file sits in a synced folder.
2. Copy the data file in File Explorer to a folder on drive C like C:\OutlookData.
3. Start Outlook and dismiss any file not found message.
4. Open Account Settings twice from the File tab and select the Data Files tab.
5. Remove the old entry and add the copy with Add.
6. Restart Outlook and test the mail.
7. Delete the old copy after you confirm everything.

Note: Removing an entry only unlinks it from the profile. Move to Method 5 when the copy fails with a CRC error.

Method #3: Check Event Viewer and Test the Drive (Free)

Anonymous advises a look at Event Viewer for disk errors and a test with the manufacturer tools. Copy your important files before you test. Four steps follow:

1. Search for Event Viewer and open it.
2. Expand Windows Logs and open System.
3. Scan for disk errors near the time Outlook failed.
4. Test the drive with the tool from the drive manufacturer.

Note: Independent Advisor links CRC errors to hardware failure. Replace a drive that shows errors again and again and restore the mail from a backup.

Method #4: Scan the PST Copy With SCANPST (Free)

Microsoft's article lists SCANPST for a damaged PST file. Backup the file first because items that are corrupted beyond repair do not return. Seven steps follow:

1. Close Outlook and go to the Office16 folder under Program Files.
2. Launch SCANPST.EXE.
3. Choose the PST copy with Browse.
4. Press Start to scan.
5. Press Repair if the scan lists errors.
6. Repeat the repair until no errors remain.
7. Open Outlook with the profile linked to the repaired file.

Note: Microsoft says the tool can recover fewer items than the .bak file. See our guide on an Inbox Repair tool that stops responding.

Method #5: Export Mail From the Unreadable PST File Using EmailDoctor Outlook PST Repair Tool (Demo Limit Applies)

Recovery software opens files that Outlook and SCANPST cannot. EmailDoctor Outlook PST Repair Tool fixes corrupt and inaccessible PST files and needs no Outlook for the repair according to the product page. Use a copy of the file as the input.

Open the Damaged Copy in the Software

Begin with three steps:

1. Open the software on a Windows PC and look at the first screen.
2. Click Add File and select the PST copy from the disk.
3. Scan the copy with Quick Scan first and use Advance Scan when the preview shows no mail.

Review the Recovered Mail and Save It

Three steps remain:

4. Expand the folder tree and browse the recovered mail.
5. Click Export then select an output format.
6. Select where to save the output and click Export.

Note: Free export stops at 25 items in a folder without Outlook. Buying a license removes the limitation.

Which Result Did You Get?

Find your result below:

Frequently Asked Questions

Author’s Verdict

Your drive or its location causes the error in most cases. Test the disk before you touch the PST file.

Move a copy onto a local disk and check Event Viewer. Repair the copy with the Inbox Repair tool when Outlook still fails.

Use repair software when the copy stops with an error. Backup the file before the repair.