Moving Document Attachments to External Storage in Business Central

October 1, 2026

Moving Document Attachments to External Storage in Business Central

Every scanned invoice, vendor packing slip, and signed sales order attachment in Business Central lives in the same place: your production database. That’s fine until it isn’t — until you’re staring at a capacity warning and realizing that years of PDFs are eating into the same storage limit as your actual transactional data. Business Central now has a built-in answer to that problem: external file storage. Here’s what it actually involves.

Concept diagram: attachments moving from the BC database to external Azure/SharePoint storage

What is external file storage in Business Central?

Direct answer: It’s a framework that lets you keep document attachments — PDFs, images, scanned documents — outside the Business Central database entirely, in a connected external service like Azure Blob Storage, Azure File Share, or SharePoint, while attachments remain fully accessible from within BC.

The files themselves move off your database and onto external storage; only the link back to the record stays in BC. Users don’t see a difference — they still open, add, and manage attachments from the same Attachments FactBox they always have. What changes is where the bytes actually live.

The Attachments FactBox on a Business Central record, unchanged whether attachments are stored in the database or externally

Why would I bother moving attachments off the database?

Direct answer: Mainly capacity and performance. Every Business Central tenant has a database size limit — 80 GB by default for production and sandbox environments, plus whatever extra storage your licensing adds — and attachments are often the single biggest driver of hitting that ceiling.

Beyond avoiding a capacity purchase, a smaller database also tends to mean faster backups, faster restores, and generally snappier performance. There’s also a cost angle: external cloud storage is typically cheaper per gigabyte than BC’s own database capacity, and it comes with features BC’s database doesn’t offer natively, like long-term archival tiers and content sharing.

Business Central database capacity usage view showing current usage against the limit

What storage providers does Business Central actually support?

Direct answer: Out of the box, BC supports Azure Blob Storage, Azure File Share, and SharePoint document libraries. The framework is extensible, so partners can add other providers (SFTP, OneDrive, etc.) through extensions if needed.

This is worth calling out because it’s broader than a single-provider setup. If your organization already leans on SharePoint for document management, you don’t need to stand up a separate Azure storage account just for BC attachments — you can point BC at a SharePoint site instead, using an existing Microsoft Entra ID app registration for authentication.

Comparison graphic of the three supported storage providers: Azure Blob Storage, Azure File Share, and SharePoint

How do I set up external storage for attachments?

Direct answer: Create an external file account for your storage provider, assign the Document Attachments scenario to it, then enable and configure the connection — all through assisted setup wizards in BC.

Create the external file account. Search External File Accounts (Alt+Q), choose Add a file account, and pick your storage type:

The External File Accounts page with the Add a file account action highlighted

The storage type selection step of the Add a file account wizard

Azure Blob Storage — needs an Account Name (a friendly BC-facing label), your Storage Account Name, an Authorization Type (SAS token or shared account key), the Secret itself, and the Container Name.
Azure File Share — needs an Account Name, Storage Account Name, authentication method and Secret, and the File Share Name.
SharePoint — needs an Account Name, plus the Tenant ID, Client ID, and Client Secret of an Entra ID app registration with access to the site, the SharePoint site/domain name, and a base relative folder path (e.g., Shared Documents/Attachments).

The connection details entry screen for an Azure Blob Storage file account

Assign the scenario. Search File Scenario Assignment, choose Assign scenarios, select the file account you just created, and assign the Document Attachments – External Storage scenario. Confirming this opens the External Storage Setup page.

The File Scenario Assignment page with Document Attachments – External Storage being assigned

Enable and configure. On External Storage Setup:

Turn on Enabled. BC warns you that you’re responsible for managing and backing up externally stored files — read it, then choose Yes.
Set the Root Folder — an existing container/folder in your storage. BC automatically builds a subfolder structure underneath it (by environment, company, table, and so on) to organize files by record type.
Decide on Delete External File on Attachment Delete. On means deleting an attachment in BC also deletes the file in storage. Off means BC just removes the link and leaves the file in place.

The fully configured External Storage Setup page, with Enabled, Root Folder, and Delete External File on Attachment Delete set

The warning dialog confirming responsibility for backups, shown when enabling external storage

How do I move attachments that already exist in the database?

Direct answer: Run the Storage Sync action from the File Scenarios or External Storage Setup page, and specify the direction — database to external storage.

This is the step that actually migrates your existing backlog of attachments; everything before this point only affects new attachments going forward. The same action works in reverse, too — if you ever need to stop using external storage, Storage Sync can pull everything back into the database so you can safely disable the feature.

The Storage Sync dialog with the direction selector for database to external storage

What should I watch out for before turning this on?

Direct answer: Four things: backups become your responsibility, Copy Company and environment restores don’t bring the files with them, broken links are possible if a file disappears outside of BC, and file names get modified behind the scenes (though users won’t notice).

Once files live in Azure or SharePoint, Microsoft doesn’t back them up as part of your BC environment. You need your own backup and retention policy on the storage side.
Copy Company / environment restore. These operations copy the attachment metadata and links, not the physical files. After a copy or restore, you need to run the Migrate Files action from External Storage Setup to re-sync the actual files into the new environment or company folder.
Broken links. If a file is deleted from external storage outside of BC — by someone with direct access to the storage account — the link in BC breaks and users get an error trying to open it. Keep access to the storage container tightly controlled.
File naming. BC appends a unique ID to each file name in external storage to prevent collisions (two records both attaching a file called “invoice.pdf” won’t overwrite each other). The attachment title shown inside BC stays as the original file name — the renaming is invisible to end users.

Comparison of the attachment title shown in BC versus the renamed file with appended unique ID in external storage

Can I still browse and manage files directly from BC?

Direct answer: Yes. The External File Accounts page includes a Storage Browser action that opens a view of the folders and files in your connected storage, where you can upload, download, delete files, or create new folders.

This is a useful way to sanity-check that attachments are landing where you expect after you first turn the feature on, or to manage files manually without leaving Business Central.

The Storage Browser view showing the auto-generated folder structure and files

Are there any known issues to check for before relying on this?

Direct answer: Yes — one confirmed bug (now fixed) around the delete-sync toggle, and one setup gotcha worth ruling out early if you’re connecting to SharePoint.

The “Delete External File on Attachment Delete” toggle didn’t always work. A bug tracked in Microsoft’s public BCApps repository (issue #8162, filed May 2026) found that turning this toggle on didn’t actually trigger a delete in external storage — deleting an attachment in BC never sent the delete request to the storage provider, so files accumulated as orphaned blobs instead of being removed. The root cause was a timing issue in the underlying event logic: it tried to look up the attachment record after BC had already deleted it, so the lookup failed and the delete request never went out. The person who filed it flagged this as a potential compliance concern for organizations relying on the toggle to actually remove data on request. The issue has since been closed with a fix. The practical takeaway: if you enabled this feature before mid-2026, it’s worth spot-checking your external storage to confirm deleted attachments were actually removed, rather than assuming the toggle worked as expected the whole time.
SharePoint connection failures aren’t always a BC configuration problem. At least one partner reported that their SharePoint external storage connection failed during initial testing, and after investigation the cause turned out to be an expired Microsoft 365 license on the test tenant — not anything wrong with the account setup steps in BC. If your SharePoint connection isn’t authenticating, it’s worth checking Microsoft 365 license status before troubleshooting the BC-side configuration.

Screenshot of GitHub issue #8162 showing its closed/resolved status

Frequently Asked Questions

Do end users notice any difference once external storage is enabled?

No. Attachments are still added and opened from the same Attachments FactBox or Document Attachments page. The only difference is where the file physically lives.

Does enabling external storage move my existing attachments automatically?

No — enabling the feature only affects attachments added going forward. Existing attachments need to be moved with the Storage Sync action, run separately.

Can I use more than one external storage provider at the same time?

Yes. You can set up multiple external file accounts — for example, one for Azure Blob Storage and another for SharePoint — and assign different scenarios or document types to each.

What happens if I need to turn external storage off later?

Run Storage Sync in the opposite direction (external storage to database) to bring the files back into BC, and then disable the scenario.