Hello guys I have the same exact problem!
I keep having a 500 error while trying to see previews on my production website.
This is what I do :
- Make a change in prismic UI for an already published document
- Click save then the preview button
- This redirects me to my website on the correct url but it shows the 500 page instead
This does seem to work locally (I've set up a preview to my localhost and this does work perfectly)
The cookie content is as follow :
The only way I found to get rid of the 500 after that is to manually remove the cookies in the application tab.
I've already tried the troubleshooting guide but this didn't help me.
I can provide a copy of my project in private message if needed, thanks for your help