so what has changed? things normally dont just stop working… wp update? plugins or themes?

have you checked this: http://codex.simple-press.com/codex/faq/troubleshooting/what-is-this-jquery-conflict/

a link to your site and we might be able to check for obvious conflicts… try a temp switch to the default wp theme too…

Sorry, forgot to add URL: www.passengerfans.co.uk/forum/

Just tried switching back to TwentyEleven and the problem remains.

Recent changes to the site have been mainly css tweaks and a few new plugins, including adding W3 Total Cache and using a CDN, (but the forum pages are excluded from the Cache) but I disabled *all* the plugins and the problem still remained.

I will PM login info if required.

what are you loading from the CDN? The forum will need to be excluded from that as well.

The forum is indeed excluded from the CDN, but the CDN is managed through W3 Total Cache, and when I disable the plugin, and therefore disable use of the CDN, it still does not work.

Sorry, there may be something else I have tweaked but I honestly can’t remember what, most of my time recently, since we resolved the jquery conflicts for quote/reply with the theme, have been on main content and css. I honestly can’t think of any major changes.

I just had a look through all the options and things, and tried deselecting ‘Load javascript in footer’, which allowed me to click on received PM’s and read the thread, but I still can’t reply or compose.

Just discovered the following in the error log which has jogged my memory:

I disabled the ‘File Uploader with Plupload’ plugin on the forum… I just re-enabled it an everything now works again.

For now, I have left it enabled but removed permissions for individuals to be able to upload (as I decided I did not want this functionality, hence disabling it!) but this would appear to be a bug as I should be able to deactivate it without a problem I would’ve thought?

doesnt look like to me that you disable the forum page from ALL types of caching in play…

<!– Performance optimized by W3 Total Cache. Learn more: http://www.w3-edge.com/wordpress-plugins/

Minified using disk: basic
Page Caching using disk: enhanced (Requested URI is rejected)
Database Caching using disk: basic
Object Caching 1200/1217 objects using disk: basic
Content Delivery Network via Amazon Web Services: CloudFront: cdn5.passengerfans.co.uk

Served from: www.passengerfans.co.uk @ 2012-11-04 21:30:20 –>

page caching is disabled, but its still object caching and minifying…  that will cause problems… especially since we already minify the js… 

can you also disable the forum page from caching for ALL types in use on W3TC??  go to each tab and where you can, tell it to ignore the page…

I will take a look at those messages… it does check for plupload, but perhaps something else is amiss there…

ah, does look like a bit of a hole there… it does check for uploader, but if both are active and you are allowing uploads, but then decide to remove the file uploader, the checks dont appear sufficient… an extra check on both having been used and one removed is needed…

will get it fixed up…

I think our posts crossed, see above – I disabled ALL use of the CDN to test this previously and it still didn’t work… but more importantly I think I found the problem!

I have deactivated W3TC completely and also disabled the File Upload plugin for SP, to demonstrate.

Thanks very much, posts crossed again!

no worries… hard at work trying to solve!