Filtering published_at yields "Request not understood error, cannot list posts."

[Heaney555]

Hi there.

We use Ghost(Pro), and we’ve been using the following query with the Ghost Content API for many months now:

https://uploadvr.ghost.io/ghost/api/content/posts/?key=[KEY]&filter=primary_author:[NAME]+published_at:>='2025-05-18'

(above, I’ve replaced the actual key and primary_author with square brackets, and used an example date)

This has worked for many months with no issues - until the past few days.

Suddenly, it is yielding:
{"errors":[{"message":"Request not understood error, cannot list posts.","context":"Error parsing filter","type":"BadRequestError","details":null,"property":null,"help":null,"code":null

It’s definitely published_at causing this, since if I remove that the error goes away.

Is this a regression, or a change to the API? What’s going on here?

[Cathy_Sarisky]

If you remember primary_author, does it work correctly?
Are you URL encoding your strings for the filter?

[Cathy_Sarisky]

Just tried on Ghost Pro.

My ‘raw’ string is: filter=primary_author:cathy+published_at:>'2025-05-18'

After encoding, I have:
https://cathys-second-demo-site.ghost.io/ghost/api/content/posts/?key=fe271d7637c1e685bc13e11f21&filter=primary_author%3Acathy%2Bpublished_at%3A%3E%272025-05-18%27 , which works fine. I’m test on Ghost Pro, which is 5.120.1-0-ge3b36eb+moya for my site today.

[Heaney555]

On further testing, this seems to only happen in Zapier WebRequest steps, and as you note, it works fine if done elsewhere.

Either something has changed with how Ghost handles URL/query decoding or something has changed with how Zapier encodes.

Regardless, I can workaround by using raw requests of my own.