Title: PHP Error in Use
Last modified: August 21, 2016

---

# PHP Error in Use

 *  Resolved [blksheep](https://wordpress.org/support/users/blksheep/)
 * (@blksheep)
 * [11 years, 11 months ago](https://wordpress.org/support/topic/php-error-in-use/)
 * Hello,
 * I’m using a premium theme – Rockford – as my primary theme and trying to use 
   other themes for other pages. It’s giving the same message when I try to use 
   any other theme:
 * Warning: join() [function.join]: Invalid arguments passed in /home/amandl5/public_html/
   blog/wp-includes/post-template.php on line 478
    class=””>
 * Many thanks in advance for any assistance – would really love for this to work–
   otherwise I’ll try multi-worpress installations I suppose –
 * [https://wordpress.org/plugins/jonradio-multiple-themes/](https://wordpress.org/plugins/jonradio-multiple-themes/)

Viewing 4 replies - 1 through 4 (of 4 total)

 *  [jon](https://wordpress.org/support/users/adiant/)
 * (@adiant)
 * [11 years, 11 months ago](https://wordpress.org/support/topic/php-error-in-use/#post-4990891)
 * I would recommend Multi-Site/Network as you mention, but there is one possibility
   that might work — obviously, I can’t test as I don’t own a license to Rockford.
 * Warning: this solution may create more new problems than it solves.
 * Take a look at the “Select Theme for Everything” Advanced Setting in my plugin.
   You would select Rockford there, then try another Theme as your Active Theme,
   and specify that Active Theme just for the Page or Post you want it just as you
   are doing now.
 *  Thread Starter [blksheep](https://wordpress.org/support/users/blksheep/)
 * (@blksheep)
 * [11 years, 11 months ago](https://wordpress.org/support/topic/php-error-in-use/#post-4990895)
 * Thanks for your response – gave that a shot, no luck. It’s the Tetris theme –
   other themes seems to be working fine and not producing this error. Oh well onward
   to multi-site-ing, which I’ve read isn’t the right application for what I’m after–
   multi sites are for large pages over many users? I’m just looking to use different
   themes for different sections, unfortunately with the Tetris theme that’s I’m
   kind of stuck on. Thanks for your help –
 *  [jon](https://wordpress.org/support/users/adiant/)
 * (@adiant)
 * [11 years, 11 months ago](https://wordpress.org/support/topic/php-error-in-use/#post-4990897)
 * Personally, I think multi-site/network is the right solution for ANYONE using
   multiple themes. As the years have passed since I first wrote this plugin, it
   became very clear to me, especially in terms of Theme Options, that WordPress
   was not developed with multiple themes (on a single site) in mind. And newer 
   Themes and even some plugins are causing incompatibilities with my plugin that
   I just can’t fix.
 * I use WordPress Networks for multiple small sites that I want to “glue together”
   so they look like one site. I’m a huge fan.
 *  Thread Starter [blksheep](https://wordpress.org/support/users/blksheep/)
 * (@blksheep)
 * [11 years, 11 months ago](https://wordpress.org/support/topic/php-error-in-use/#post-4990906)
 * Thanks so much for the insight. I did a re-install with multi-site option, everything
   is working excellently, I’ve got my two themes with a single install, brilliant.
   The learning curve doesn’t seem bad at all. Thanks again for your help –

Viewing 4 replies - 1 through 4 (of 4 total)

The topic ‘PHP Error in Use’ is closed to new replies.

 * ![](https://ps.w.org/jonradio-multiple-themes/assets/icon-256x256.png?rev=1134086)
 * [Multiple Themes](https://wordpress.org/plugins/jonradio-multiple-themes/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/jonradio-multiple-themes/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/jonradio-multiple-themes/)
 * [Active Topics](https://wordpress.org/support/plugin/jonradio-multiple-themes/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/jonradio-multiple-themes/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/jonradio-multiple-themes/reviews/)

 * 4 replies
 * 2 participants
 * Last reply from: [blksheep](https://wordpress.org/support/users/blksheep/)
 * Last activity: [11 years, 11 months ago](https://wordpress.org/support/topic/php-error-in-use/#post-4990906)
 * Status: resolved