Power Platform Community Forum Thread Details

My flow fails with the below error message.

The message exceeds the maximum supported size

In Power Automate, OUTLOOK Attachment size limit is different from an array variable size limit?

If so, what are they?

Thank you,

SueA.

Categories:

Building flows

Hi @SueA,

Yes, the Outlook attachment size limit and the array variable size limit in Power Automate are different and can cause your flow to fail with a "message exceeds the maximum supported size" error.

Outlook Attachment Size Limit: The maximum size for attachments sent via the Outlook connector in Power Automate is typically 25 MB to 50 MB depending on the connector and tenant settings. If your attachments exceed this, the email send action will fail.
Array Variable Size Limit: Power Automate array variables do not have a strict character limit like 8,000 characters, but the overall flow run has memory and size limits. Large arrays or variables can cause performance issues or failures if they grow too large (tens of MBs). Also, the flow designer limits expression sizes to around 8,192 characters, which can affect building large arrays dynamically.

If your flow involves sending large attachments or building large arrays, you may hit these limits separately:

For large files, consider uploading them to SharePoint or OneDrive and sending a link instead of attaching the file.
For large arrays, try to reduce the size by filtering or batching, or store data externally (e.g., Dataverse, SharePoint) instead of in variables.

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