To resolve the error fetching dynamic fields in HubSpot, we need to troubleshoot the "Body parse output" 400 error. Here are some steps to help:
1. Check your key formatting: Ensure all keys are surrounded by double quotes.
2. Review punctuation and syntax: Verify that keys are separated by commas and watch for extra spaces, colons, or brackets.
3. Look for hidden characters: Copy and paste your body into a text editor to spot any hidden characters.
4. Verify the API key: Make sure you're using the correct API key for HubSpot.
To help troubleshoot further, could you please copy and paste the JSON you're using into the chat? This will allow me to take a closer look at the specific issue.