Internal server error 500 is one of the most common problems bloggers bump into when tweaking their blogs. The error appears when trying to access your live blog or the blog and the Admin panel. You get a notification like this one:
Internal server error 500

Stumbling upon Internal Server Error for the first time is scary. No worries! Almost every blogger out there has dealt with it at some point.
The server encountered an internal error of misconfiguration and was not able to process your request.
Please contact the server administrator… and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
You might see this message every now and then making you believe that there’s something wrong with the server or you might stumble upon it once without being able to get rid of it. In both cases we’re talking about malfunctions, most likely caused by some misconfiguration or an incompatibility issue which you must take care of.
Solving the Two Most Common Causes of Internal Server Error
There’re two most common reasons why you see this error message: a theme or a plugin on your blog is causing issues due to bad coding or incompatibility; or a misconfiguration in relation to URL change occurred.
Plugin/Theme incompatibility
If you haven’t been tweaking your site’s URL lately – as for example trying to move it from http://www.example.com/mysite to http:/www.example.com, we’re most likely talking about plugin or theme incompatibility issue.
As long as you’re able to log into your Admin panel in WordPress, you can easily go to the bottom of the issue: simply disable all your plugins and check whether the issue has been resolved. If yes, start enabling your plugins one by one to identify the one causing you troubles. Disable and remove the plugin and, if necessary, replace it with an alternative.
If the issue’s still present after disabling all plugins, try cleaning the cookies in your browser to get a fresh view of your blog. If you still can’t access it, we’re likely talking about theme incompatibility. Disable your current theme and try using one of WordPress’ standard themes (with plugins still disabled). Check whether the issue has been resolved. If yes, it might mean that your theme is incompatible with the version of WordPress you’re using and you need to change it.
Be aware, that such errors can occur not only in relation to new installations but also updates and upgrades. Especially if using free themes and plugins which aren’t getting the necessary timely updates, you might end up in a situation where you no longer can use them with the newest version of WordPress. Some people would in such case advice you to get back to the pervious version of WordPress with which your configuration worked. This is, however, bad advice as you’d be risking the security of your blog.
If you can’t access the Admin panel in WordPress, the task becomes a bit more complicated and requires that you have access to your core files on the server. By using FTP or File manager, you have to navigate to public_html->wp content->plugins. From here there’re two ways to do this: you can rename your whole plugin folder to disable all plugins at once or you could go through them one by one checking the result after each change you make.
Personally, I prefer the second method. Especially if you have some idea which plugin might be the sinner, you go directly to its folder and rename it to, for example, plugin_no. Check whether the issue’s gone. If not, continue disabling the rest of the plugins the same way until you find the one causing you troubles.
Again, if it turnes out that no plugin is causing the error, take a look at the theme you’re using. Rename it’s folder which will force WordPress to fall back to its standard theme and check whether the issue has been resolved. If yes, you have to consider using another theme.
If this doesn’t resolve the issue, contact your server administrator to check whether there isn’t a problem on the server. As a last resort, you might try to use a backup of your blog from before the error occurred in an attempt to identify/resolve the issue.
URL misconfiguration
Many try – for different reasons – to change the URL of their blog and it can often cause troubles if done wrong. If you’re unable to access your blog after attempting to change the URL, you have to go in the core files of your installation and manually clear the mess.
There’re different ways to do this, but I’ll only walk you through the 2 easiest.
The first method is by editing wp-config.php (you can find this file on the server where your core WordPress files are installed). You should download the file and add the following lines:
define ('WP_HOME','http://www.newlocation.com');
define ('WP_SITEURL','http://www.newlocation.com');
This should help your blog get online again.
The second method is to edit functions.php. This file is also accessible on your server in the theme directory via File Manager of FTP. You have to download it and edit it in a text editor. You have to add the following lines right after the <?php line:
update_option ( 'siteurl', 'http://www.newlocation.com');
update_option ( 'home', 'http://www.newlocation.com');
Now you should upload the file back on the server to its original location and load the login page a few times. Your blog should be back up and running.
This is, however, not the end of the story. Now, that your blog is correctly set again, you have to go in and remove the lines you added. This is done by once again downloading, editing, and uploading the file to your theme’s directory.
In some cases your theme might not have a functions.php file. In such case you should create one in a text editor and add the exact same lines as described above. You should, however, also add the <?php tag in the beginning and the ?> tag at the end. This file should then be uploaded to your theme’s directory and deleted in the end of the process, once your blog is up and running again.