Error in revslider after updating to 6.8.12

[Juanjo]

Hi,

After updating the Pro theme to version 6.8.12, the site hotelterra.es is showing the following fatal error on wp-admin/plugins.php:

“call_user_func_array(): Argument #1 ($callback) must be a valid callback, class RevSliderAdmin does not have a method ‘add_ajax_footer_functionality’”

I have RevSlider 7.1.4 installed. I’ve already fully reinstalled the plugin via FTP and the error persists. I noticed in your changelog that this type of issue (“RevSlider was using a deprecated method on version 7”) was fixed in 6.8.6, but I’m still getting the error on 6.8.12.

Could you let me know if there’s a specific RevSlider version compatible with Pro 6.8.12, or if this could be caused by a partial theme update? I can provide FTP/WP access if needed.

Thanks.

[prakash_s]

Hello @Juanjo,

Thanks for writing to us.

I tested this on my local installation and was unable to reproduce the issue. It is working as expected with the following environment:

• Pro Theme 6.8.12
• WordPress 7.0.2
• Slider Revolution 7.0.15
• PHP 8.2.4

To help you with your concerns, we need to check your settings. I would request please share the admin login details. Meanwhile, I would suggest you troubleshoot a few of the common issues before we investigate your settings. Please share your details in a secure note. Please provide the following details

• WordPress Login URL
• Admin-level username and password
• Exact page URL

You can find the Secure Note button at the bottom of your posts

Thanks

[Juanjo]

Hi @prakash_s

Just wanted to follow up on this with a bit more context. My site was throwing a fatal error on the Plugins page whenever Slider Revolution was active — it completely disappeared as soon as I deactivated it, so I dug into it a bit myself before reaching out.

I found the actual cause: in revslider-admin.class.php (line 543), there’s a leftover add_action('admin_footer', ...) call pointing to a method called add_ajax_footer_functionality that doesn’t exist anywhere in the 7.1.4 codebase anymore — looks like it got left behind after the v7 rewrite. It only triggers when the license isn’t validated, which is probably why not everyone is hitting it.

I’ve applied a temporary fix by commenting out that line, so my site is back up and running for now. But obviously I’d rather not have to redo that patch every time the plugin updates, so I wanted to flag it properly in case it helps you track it down faster on your end.

Happy to share the exact file, the PHP error log, or anything else that’s useful for reproducing it. Thanks for looking into it!

[ruenel]

Hello @Juanjo,

I want to commend you on your excellent troubleshooting work. You’ve not only identified the source of the fatal error but also implemented a temporary fix and provided incredibly useful context about the license validation trigger. That’s a huge help for our team, and I truly appreciate it.

Your fix—commenting out the add_action call—is a clean and safe temporary patch. For your reference, after the issue is permanently resolved (by a plugin update from RevSlider), you can restore that line during the next update to ensure no future conflicts.

Thank you again for your detailed report and for being such a proactive member of the Themeco community. Your insights are invaluable. Please let us know what you decide to do, or if you have any other questions. We’re here to help!

Best Regards.