Multiple users are experiencing an issue with the Post Preview feature in Discourse not working due to the events plugin. diabolicvincent first reported the issue, which persists even with different themes and all components disabled. However, the issue does not occur in safe mode. Further investigation revealed that the issue only happens when replying to a specific topic using the “Reply” button next to the Heart, not when using the blue “Reply” button at the bottom of the topic. Falco identified the source of the problem as the events plugin, which is a third-party plugin. diabolicvincent confirmed that they have the discourse-events plugin enabled. Other users, including OldRoutard and vincentp, are experiencing similar issues, including problems with syntax highlighting and inserting hyperlinks. Falco advised reporting the issue on the plugin topic, as it is not a core nor official plugin.
What about safe mode? Is there anything in your browser console? What plugins do you have installed? Are you on tests-passed, did you rebuild recently?
Thanks for letting me know about safe mode, Sam! It does not seem to happen with plugins disabled. We’re running on tests-passed and did not undergo any rebuilds recently.
The following plugins are enabled:
Can you share the forum URL ?
Unfortunately that won’t be of much help, as the forum has restricted access.
Though, I discovered something else: The Post-Preview only disappears when replying to a specific topic using the “Reply” Button next to the Heart.
When using the blue “Reply” Button at the bottom of a topic it works just fine.
That usually happens when the site HTTPS is misconfigured. Can you check the DevTools logs when the issue happens? Both the console and network tab will show you why it’s happening.
Greetings Discourse people.
Just to say that we are seeing this problem in the Fairphone forum too, seemingly since updating to v.2.9.0 beta 5 and 6. You’ll find a thread here.
I confirm this seems only to happen when the new post is begun by clicking the grey “Reply” button of a preceding post. Using the blue general Topic Reply, or using “Quote” to initiate the post, does not produce the issue.
We observe other (JS - related?) issues at the same time, for example the “Quote”, and inserting a hyperlink (the optional title field is not populated and the dialogue cannot be validated). These issues are not seen if the post was not initiated by clicking a grey “Reply” button.
I also confirm that the issues have not been seen in safe mode.
I’m seeing the same issue on 1 of the 2 discourse instances I manage - https://forums.adug.org.au/
It doesn’t happen in safe mode, but dev tools doesn’t show any errors either.
I’m also seeing that syntax highlighting no longer works - it looks like the theme css is resetting the hljs styles - using the default theme - also doesn’t happen in safe mode.
That means that there are error in the Fairphone theme. It must be fixed by an admin there. It appears that, for example, there is a theme-component trying to use the old deprecated Discourse.User global object.
In my case the instance is using the Default theme.
I tried signing up for it, but it’s on the moderator queue 
Approved now.. we get a lot of spammers signing up.
It’s broken because of a third party plugin: Events Plugin 📅
Please report on the plugin topic as this is not a core nor official plugin.
Looks like it’s the same for
Thanks Falco for pointing out the source of the problem very quickly!
