413 “Request Entity Too Large” when uploading IMAGE asset via REST (AssetService)

[Marcell Buglyó]

Hello!

I'm trying to setup an automated asset uploader via the API, however I'm getting stuck at the same error:

Environment

• Integration tool: n8n (HTTP Request node)

• API: Google Ads API v21 (REST)

• Endpoint: POST https://googleads.googleapis.com/v21/customers/{CUSTOMER_ID}/assets:mutate

• Auth: OAuth2 (scope https://www.googleapis.com/auth/adwords)

• Headers:

  • developer-token: <DEV_TOKEN>

  • login-customer-id: <MCC_ID> (when applicable)

• Customer/MCC IDs sent without dashes

What I’m doing

• I download an image from Google Drive in n8n (binary).

• I send the image to AssetService as base64-encoded bytes in JSON:

  { "operations": [ { "create": { "name": "Marketing Image", "type": "IMAGE", "imageAsset": { "data": "{{ $json.image_b64 }}"} } } ] }

• Same payload structure as the client library sample (which uses ImageAsset.data bytes), but via REST/JSON.

Result

• The request fails with HTTP 413 – Request Entity Too Large.

• HTML response from Google front end (GFE) with the standard 413 page.

• The file I'm testing with is a 1200x1200 image with a 1MB Size

I would appreciate some help on what I'm doing wrong, or what I didn't take into consideration :)

Thank you,

Marcell

[Google Ads API Forum Advisor]

Hi,

Thank you for reaching out to the Google Ads API support team.

As per provided information, I understand that you are encountering ‘HTTP 413 – Request Entity Too Large’ when trying to create ImageAsset through the Google Ads API. This error indicates that you are uploading a large file. Please note that the maximum file size is 5120 KB but you are uploading 1MB size so that you are getting this error. I would recommend you to upload the image file size within 5120 KB. I would suggest you refer to the Image assets format requirements help center article for more detailed information.

If you still face any issues, please feel free to contact us.

Thanks,
 

Google Ads API Team

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[2025-09-15 10:11:20Z GMT] This message is in relation to case "ref:!00D1U01174p.!500Ht01u6bxX:ref" (ADR-00332744)