Why Do PDF and TXT Files Change Extensions When Downloaded Using n8n?

Based on what others have experienced, this behavior usually results from how the file's metadata is handled when the binary data is passed along in the workflow. In many cases, the file name (and its extension) isn’t preserved exactly as it comes from Google Drive. For example, a file originally named "document.pdf" might be renamed to something like "document.pdf_" if the node that downloads or processes the file isn’t using the original name property.

A common workaround is to explicitly reset or update the file name. Here’s one way to address it:

1. Retrieve the Original File Name:
   The Google Drive node returns metadata (for example, via its JSON data) that includes the original file name. Make sure to extract this name.

2. Override the Binary Data Name:
   Use a Set node (or Function node) to update the binary property’s file name to what you expect. For example, if your binary data is in a property called data and you want to ensure it uses the original name, you can set it using an expression.

Below is an example using a Set node:

JSONCopied
[
  {
    "name": "Set File Name",
    "type": "n8n-nodes-base.set",
    "parameters": {
      "values": {
        "binary": [
          {
            "name": "data",
            "value": "={{ $json.name }}" // Assumes 'name' is the original file name from Google Drive
          }
        ]
      }
    },
    "typeVersion": 1,
    "position": [
      680,
      300
    ]
  }
]

Tips:

• Double-check the property name (like name or fileName) that contains the original file name in your Google Drive node’s output.
• If necessary, add a Function node to conditionally append or correct the extension. For instance, if you know the file should be a PDF, you can forcefully set it to end with .pdf.

This approach should help ensure that the final file you output in your workflow has the proper extension. If the issue persists, it might be worth looking into your binary data settings (for example, whether you’re in memory mode or filesystem mode) as described in the documentation for handling binary data.

Let me know if you need further assistance on setting this up!