How to use Missing Attachments Scanner for Confluence

Introduction

The Missing Attachment Scanner performs a comprehensive background scan on all the attachment files in all spaces (including those in trash).

By identifying the missing attachments, it helps to

prevent (unknown) data loss
facilitate data recovery with earlier discovery
identify any underlying issues
reduce the errors logged in Confluence backend
fix broken links in the Confluence pages

How to know when attachments are missing

It is not possible to eyeball missing attachments from the Confluence page.

If they are rendered on the Confluence page, you may spot “? Unknown Attachment”

Otherwise, you only detect it when a user clicks on the link to download it.
The following error message like this will appear in atlassian-confluence.log

CODE

getAttachmentData Could not find data for attachment: 
Attachment: image2022-1-8 11:48:26.png v.1 (873607111)

Some possible reasons for missing Confluence attachments

Files being removed accidentally
Files not fully copied over during server migrations or space imports
Malicious attacks caused by trojans or ransomware
Files quarantined by virus scans with updated virus definition files
Errors during the file uploads/deletion
Incomplete page move operations (👉 before Confluence 8.1)
File/Folder permissions set wrongly
Confluence disk space full

You can also check the Large Attachment Checker to identify the contributors to disk full issue

How to access Missing Attachment Scanner

It can be accessed from the admin sidebar.

How to trigger a scan

Since there may be a lot of attachments in the Confluence instance, we recommend to schedule the scanning during off-peak hours

Click on the pencil icon for Scheduled Time to adjust the time for scanning
The Scan Status will be updated progressively whenever it has scanned 1 new space

When the Rescan button is clicked, it will trigger a fresh new scan

What to do with the results

With the report on missing attachments, admins can try to reinstate back the missing files or delete the corresponding database records.

Reinstate the missing files

Try to locate the file in the quarantine folder or from the backups
Click on the info icon to find the location of the missing attachment
Copy the file back to the location in the Confluence server
Verify that the restored attachment can be downloaded from the Confluence page

Remember to rename the file to the version number.

More info about Confluence’s attachment directory structure.

Delete the corresponding database record

If the attachment cannot be restored, it will be better to clear the database record with the following steps

Click on the bin icon to delete the database record of the missing attachment
Click on Delete button to confirm

It is possible to bulk delete all the missing attachments by clicking on Purge All button.

When to trigger a scan

Ideally, we recommend to do a scan

before and after a version upgrade
before and after any server migration