TL;DR: A single Power Automate message is limited to 100 MB. Enable Allow chunking under an action’s Settings → Content transfer and supported actions handle files up to 1 GB.
Uploading or copying a large document in a flow suddenly fails with a size or timeout error? You have hit the 100 MB message size limit that applies to a single HTTP call in Power Automate. For actions that support it, switching on Allow chunking raises the ceiling to 1 GB by splitting the payload into smaller pieces automatically.
💡 Challenge
Your flow moves, uploads or downloads a file — a big PDF, video or backup — and the run fails or times out once the file grows past roughly 100 MB. That is expected: the limit on a single message in an automated, scheduled or instant flow is 100 MB, and when you send a file through a connector the whole payload (headers, metadata and file) must stay under that limit — not just the file itself.
✅ Solution
Many file actions can transfer larger content in pieces instead of one block. Turning on Allow chunking in the action’s Content transfer settings lets supported actions process files up to 1 GB. The chunking protocol is handled for you — you do not split anything manually.
🔧 How it’s done
1. Open the action’s settings.
🔸 On the file action (e.g. Create file, Get file content, HTTP), open the … menu → Settings.
2. Enable Allow chunking.
🔸 Scroll to Content transfer and set Allow chunking to On. Save the action.
🔸 With chunking on, supported actions handle payloads up to 1 GB instead of 100 MB.
3. Don’t feed chunked actions from the trigger or a variable directly.
🔸 Chunking is not supported on triggers. If you reference triggerBody(), a variable or an inline expression as the content, chunking is disabled.
🔸 Store the content in a Compose action first, then point the chunking-enabled action at that Compose output.
4. Confirm the connector actually supports chunking.
🔸 Not every connector or API supports chunking — some don’t even honor the default 100 MB. If an action doesn’t expose the toggle or still fails, the underlying connector doesn’t support it.
5. For files well beyond 1 GB, copy server-side.
🔸 Skip downloading and re-uploading the bytes through the flow. Use a server-side copy — e.g. Azure Blob Copy Blob From URL with a Microsoft Graph @microsoft.graph.downloadUrl — so the file never passes through Power Automate’s size limits.
🎉 Result
Large-file actions that used to fail at ~100 MB now transfer content up to 1 GB with a single settings toggle — no premium connector, no restructuring, and no manual splitting.
🌟 Key Advantages
🔸 One toggle: Allow chunking is a per-action setting, not a redesign.
🔸 10x headroom: 100 MB → 1 GB on supported actions.
🔸 Built-in: works with standard HTTP and many standard file actions — no premium licence required.
🛠️ FAQ
Q1: What exactly is the limit — 100 MB or 1 GB?
A single message is 100 MB by default. With Allow chunking enabled on a supporting action, the limit rises to 1 GB.
Q2: Why does my flow still fail after enabling chunking?
Either the connector doesn’t support chunking, or the content comes straight from a trigger/variable/expression (which disables it). Route the content through a Compose action and verify the connector supports chunking.
Q3: Does chunking work on triggers?
No. Chunking applies to actions only. A trigger can’t deliver more than the default limit, so pull large content with a separate action after the trigger.
Q4: The file is 3 GB — what now?
Chunking tops out at 1 GB. For larger files, use a server-side copy (e.g. Azure Blob Copy Blob From URL with a direct download URL) so the bytes never flow through Power Automate.
Q5: Enabling chunking removed my Overwrite option — is that related?
Yes. Some SharePoint actions hide Overwrite when chunking is on. See #PowerPlatformTip 27 for the reverse trade-off.
🔗 Related Tips
- #PowerPlatformTip 27: Overwrite Existing Files in Power Automate — the reverse trade-off: turn Allow Chunking off to unlock the Overwrite toggle.
- #PowerPlatformTip 58: HTTP Actions — HTTP actions are the main chunking candidates for custom API calls.
- #PowerPlatformTip 18: Download & Save Files — choosing the right action for public vs. authenticated file handling.
Marcel Lehmann
Microsoft MVP