Know How Resolve ‘Attempting to Validate BBT Refcounts’ Outlook Error
If you’re seeing the Outlook error “Attempting to validate BBT Refcounts” or “Couldn’t find BBT entry in the RBT (211C8)”, it indicates corruption in your Outlook data file (PST). This usually happens when the Block B-tree (BBT) structure inside the PST file becomes damaged due to reasons like abrupt shutdowns, malware infections, or oversized mailboxes. When this corruption occurs, Outlook’s built-in repair utility (ScanPST.exe) often fails to restore the file, displaying this specific validation error. In this comprehensive guide, we’ll explain why Outlook shows the “Attempting to validate BBT Refcounts” error, what it means, and how to fix it using both manual and professional methods.
Securely Resolve “Attempting to validate BBT Refcounts” Issue
A quick and reliable approach to resolving the isue safely. The SysTools PST Repair Tool is one of the best solutions to repair and save data in various file formats.
The software is designed on highly programmed algorithms, with support to fix both major as well as minor corruptions. It comprises a user-friendly interface so that every technical and non-technical user can operate it without any hassle.
Understanding the “BBT Entry has Different Refcount in RBT” Error
PST file of Microsoft Outlook is the central location to store all emails, contacts, calendars, tasks, journals, and all other data items. There are various factors that can cause PST File error such as improper Outlook shutdown, virus or malware attack, fault in the application and so forth. After corruption, when a user tries to recover corrupted PST file via Scanpst.exe then, it may happen that PST becomes completely inaccessible or throws an error message that says ‘Attempting to validate BBT Refcounts’. Or, sometimes the same error displays as “Couldn’t find BBT entry in the RBT (211C8)” in the log file as shown below:
Opening the log file will display the error as :
When attempting to repair again with Scanpst.exe it displays “Only minor inconsistencies were found in this file. Repairing file is optional. To repair it, click Repair “(with no Repair Button) as shown below:
Getting this error prompt means the inbox repair tool fails in the repair process and it leaves the corrupted PST file unaffected. If there is severe corruption in file then, the tool fails to repair it and results in the mentioned error. Also, when Outlook becomes unable to get the BBT entry of file, it displays the same error.
It is important to fix this issue because PST files are so sensitive and these kinds of errors can lead users to permanent data loss. There are many proactive Outlook users who maintain a backup of their account’s data and utilizes the backup when PST gets corrupted. Users who do not have the backup Outlook.com data file still can get data back from PST file. In this editorial, we have compiled some manual as well as professional workarounds to resolve Outlook error i.e. Attempting to validate BBT Refcounts or Couldn’t find BBT entry in the RBT.
Why This Outlook Error Occurs?
Several underlying causes can trigger this PST validation failure:
- The PST file has exceeded the recommended size limit (especially in older Outlook versions).
- Improper system or Outlook shutdowns during data sync.
- Faulty or incompatible add-ins that interfere with PST integrity.
- Malware or virus infections that damage Outlook data.
- Registry corruption or incomplete Outlook installation.
- Repeated or interrupted ScanPST repair attempts.
Manually Fix Error “Attempting to validate BBT Refcounts”
- Eliminate the possible causes
- Disable unnecessary add-ins
- Reinstall MS Outlook application
Approach 1: Eliminate the Possible Causes
The main cause of this error message is exceeded the size of Outlook PST file. Hence, one can compress PST file via deleting the unnecessary email messages from Inbox, Drafts, Sent Items, Conversion History, and all other folders. After that, empty the Deleted Items folder. Doing this will release the PST file size and it will resolve the Outlook error ‘Attempting to validate BBT Refcounts’.
Limitation:
If deleting emails will not reduce the size of PST file then, the error will not be resolved
Approach 2: Disable Add-ins
Corrupted add-ins also lead to the file corruption. Thus, it is better to disable Outlook add-ins. Here is how to do this:
- Navigate to Outlook Add-ins and click on Tools
- Select Trust Center option and disable the additional Add-Ins
Limitation:
Add-ins may not be the reason for corrupted file hence might / might not resolve error Couldn’t find BBT entry in the RBT (211C8)
Approach 3: Reinstall Microsoft Outlook Application
The corrupted Outlook registry may lead PST file to corruption. One can reinstall Outlook to get rid of the mentioned error. To do this:
- Open Control Panel and go to MS Outlook email client
- Here, select Outlook and Uninstall the current email application
- After that, reinstall Outlook
Limitations:
It is possible that Outlook PST will remain corrupted even after reinstalling the email application.
Freshly installed Outlook will leave you with no database
Final Verdict
There are many causes, which may lead an Outlook PST file, to corruption. Scanpst.exe is the basic utility that all users opt as their first approach to fix PST file. However, what if this inbuilt Outlook utility makes PST file completely inaccessible or fails to repair may result in various error messages like ‘Attempting to validate BBT Refcounts’? Creating the backup of Outlook data is a good habit to prevent these conditions, however, if one has not created the backup then, this blog includes some simple manual solutions to resolve the issue. Yet, manual methods sometimes fail to repair file. Then, users can use the above mentioned automatic solution to get rid of the mentioned Outlook error. This professional software recovers data in the least possible time, even without any data loss.