Are you seeing this error message at the top of every page of your WordPress blog? (The fix is below…)
Warning: sem_get() [function.sem-get]: failed for key 0x152b: Permission denied in /home/username/public_html/wp-content/plugins/wp-cache/wp-cache-phase2.php on line 98
You might also be getting something like this at the foot of every page too:-
Warning: sem_acquire(): supplied argument is not a valid SysV semaphore resource in /home/username/public_html/wp-content/plugins/wp-cache/wp-cache-phase2.php on line 107
You’re not the only one. Google is full of sites showing this error (about 50,000 pages on this quick search):-
If you’re seeing this error, you probably can’t log in to the admin area of your blog either! Here’s how to fix it.
How To Fix It Fast
The error is coming from one of your plugins called WP-Cache. It’s the plugin that is supposed to help speed up your blog. But this plugin is now very old and hasn’t been updated for years. (For a better one keep reading below).
1. Get Your Blog Working
Top priority – let’s make this error go away.
You need to disable that plugin. You probably can’t login to the WordPress admin area due to the same error. But you can get round this by editing your WordPress config file (wp-config.php) which you’ll find in the folder you installed your blog.
NOTE: be very careful editing this file, as you can break your blog even more. I recommend you keep a backup copy before making any changes.
Edit the wp-config.php file and remove this line:-
(If your host uses cpanel, you can edit using the built in code editor. Otherwise download using FTP, edit, then upload the amended version)
You should now be able to log in to your blog admin area. Now go to your plugins and disable WP Cache.
Your blog should now be functioning normally without showing any errors.
2. Now Install WP Super Cache
If your blog gets very little traffic, you may want to leave it at that. Especially as installing WP Super Cache isn’t particularly easy.
WP Super Cache does what WP Cache used to do well. The most critical difference being that WP Super Cache is still actively being developed. Which is important when WordPress keeps changing and improving all the time.
You can download it here:-
NOTE: Follow the install instructions in the Read Me very closely. Especially the instructions about removing left over traces of the old WP Cache.
3. Please Link To This Page
If this fixed your problem, please send a link to this page. It will help the other 50,000 or so blogs suffering the same thing! Thanks.
So Why The Errors?
In short, I don’t know yet. But I’d be interested to hear if anyone knows?
I’ve seen a whole bunch of blogs all suddenly display this error. Those blogs were all hosted with Bluehost, so maybe a change Bluehost have made has caused WP Cache to fail? That’s not to say it’s the fault of Bluehost as WP Cache is old and unsupported code.
Have you seen this error on your Bluehost blogs? Or on blogs hosted elsewhere?
Or do you know what is causing the errors?
Please leave a comment below. Thanks.