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Power Platform Community / Forums / Power Automate / Power Automate Approva...
Power Automate
Suggested Answer

Power Automate Approval - Attachments not opening

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Posted on by HT-13010703-0 2

Problem:
I'm using Start and wait for an approval action in Power Automate. The attachments are appearing in the approval email, but when I try to open them, they don't work. The files show up with correct names but won't open.

My Flow:

  1. Initialize variable: Emailattachmnets (Array) = []
  2. Get Document Attachments (Custom API that returns files with base64 encoding)
  3. Apply to each (looping through API response)
    • Append to array variable: Emailattachmnets
    • Value: {
        "name": "@{items('Apply_to_each')?['fileName']}",
        "content": "@{items('Apply_to_each')?['attachmentBase64']}"
      }
  4. Compose (for testing) - Shows correct output with 2 files

  5. Start and wait for an approval - Attachments: @variables('Emailattachmnets').

What's Working:

  • Files appear in approval email with correct names
  • Compose action shows proper array structure
  • Base64 strings are clean (no line breaks or spaces)


What's NOT Working:

  • Files won't open when clicked in approval email

  • Seems like base64 is not being properly decoded/converted

What I've Tried:


  • Using @outputs('Compose') instead of variable - same issue

  • Different field name variations (name/Name, contentBytes/ContentBytes)

  • The array structure looks correct in Compose output

Any help would be appreciated! Has anyone successfully sent multiple base64 attachments through approval emails?

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Categories:
Power Automate Desktop
I have the same question (0)
  • Suggested answer
    chiaraalina Profile Picture
    chiaraalina 2,425 Super User 2026 Season 1 on at
     
    The attachment payload has to contain binary bytes, not a plain base64.
     
    Have you tried:
    {
      "name": "@{items('Apply_to_each')?['fileName']}",
      "contentBytes": "@{base64ToBinary(items('Apply_to_each')?['attachmentBase64'])}"
    }
     
    Let me know if it works!
  • HT-13010703-0 Profile Picture
    HT-13010703-0 2 on at
    Yes I have tried this approach.

    I have used content instead of contentBytes. While using content faced the below error.


    When I am trying to it by using content, I can open up the pdfs but they are coming blank.

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