How do I forward a Gmail PDF attachment using n8n while resolving the 'no binary field data' error?

Below is an explanation of what’s happening and how you might resolve the error you're encountering.

What the Error Means

The error message

The item has no binary field ‘data’ [item 0]

indicates that a node in your workflow is trying to access a binary property called “data” on the item. In other words, the attachment isn’t available under the key “data” in the current item’s binary data.

Why This Happens

When the Gmail Trigger node picks up a new email, the binary properties (like attachments) often use a specific key name determined by the node’s implementation. In your case, what you expect to be under “data” might actually be stored under a different name (for example, something like “attachment,” “binary,” or even a dynamic key based on the email structure).

How to Troubleshoot and Fix

1. Inspect the Node’s Output:
   Check the output of the Gmail Trigger node. Look under the “binary” section of the output to see what keys are available.

   • In your n8n editor, click on the node and then on “Output” to see the structure of the data.
   • Note the key name under which the PDF attachment is stored.

2. Adjust Your Workflow:
   Once you know the actual key name (for instance, if it is “attachment” instead of “data”), you need to update the node that sends the email so it uses the correct binary property.

   • If you’re referencing the attachment in an Expression or within the node’s parameters, change the expression from something like {{$json["binary"]["data"]}} to {{$json["binary"]["attachment"]}} (using the proper key name from the output).

3. Use a Function or Set Node if Needed:
   If you need the field to be named “data” for the sending node, you can use a Function or Set node to copy or rename the binary field:

   JAVASCRIPTCopied
   // In a Function node after the Gmail Trigger node
   items.forEach(item => {
     if (item.binary && item.binary.attachment) {
       // Copy the attachment to a binary field called "data"
       item.binary.data = item.binary.attachment;
     }
   });
   return items;

   Adjust the key names as appropriate, based on your Gmail Trigger node output.

4. Review the Help Articles:
   While you mentioned you have already tried several help articles, confirming how the Gmail Trigger node outputs attachments and ensuring that you are referencing the correct binary field is crucial. Some workflows require re-mapping of binary fields if multiple service integration boundaries exist.

Using these troubleshooting steps, you should be able to correctly reference the attachment binary data in your workflow and eliminate the “no binary field ‘data’” error when sending the email.

If you continue to have issues, please share a bit more detail regarding how you’re accessing the binary field in the sending node, and we can take a closer look.