Solution to our "refresh" & PM problem - apache cache settings... go figure!

[icnjill]

I posted a few weeks ago that we had begun experiencing problems after we transitioned to a new dedicated server. Specifically, some users couldn't see their PM's for a period of time, couldn't see their "replies" to posts... and couldn't use the "new post" pull down menu. Vbulletin staff suggested that it was a problem at their end since we could not reproduce the error... i.e. cookies or perhaps other software.

I am happy to report that with the assistance of logician (vbulletin.com), we have resolved the issue entirely. It turns out that the problem was in the Apache settings on the server. Here's more info for anyone else struggling with strange, random performance on new servers.

Yes, it is true that caching is usually handled on the browser/application end but Apache DOES have such an option as well. It is possible to configure apache to apply caching on server end by "mod_expires" and
"mod_headers" in "httpd.conf". More info on this procedure can be found at: http://www.websiteoptimization.com/speed/tweak/cache/

And your server is using "mod_expires" module in apache configuration.
Until yesterday it was also caching content on server level for "86400
seconds". I confirmed this in PHP info page which tells me all about server
configuration. Yesterday "Cache-Control" setting in phpinfo was set to
"max-age=86400". Today it is not, so I assume they changed it after your
ticket. However I can still see "mod_expires" is active in the server.....

Now that we have removed both settings, our vbulletin is performing well again. Thanks to everyone who tried to help. I think we all learned abit with this one.

Jill

[Steve Machol]

Thanks for that info Jill. That's another potential cause to add to the list.

It doesn't totally explain why this only happened to certain people though and could not be reproduced. I suspect the issue was still somehow related to their browser cache.

[BMamba]

@icnjill Thank you! I'm so happy I finally found the problem solution.

Unfortunatly I don't know how to fix this on my server.
I've tried to delete mod_expires and mod_headers in httpd.conf but when I did, I couldn't run httpd :/

Could any1 help me with that? Any idea?

[Logician]

It doesn't totally explain why this only happened to certain people though and could not be reproduced.

It was happening to some people because other people were overriding server cache setting with their browser's cache setting. ("check for newer versions of the store pages in internet options"/temp internet files/settings.) The poor members who set it to "automatic" were having the problem as they inherited apache setting.