What causes 500 internal server error?

SMTP error 550: how to fix “Requested action not taken: mailbox unavailable” and other SMTP 550 error messages

• 06.09.2019
• Technical matters

If you want to send a message with your e-mail client and the sending fails, you’ll receive a corresponding error message from the server, including an SMTP status code. For example, the message “550 Requested action not taken: mailbox unavailable” means that the targeted address couldn’t be reached. Since this problem can have various causes, even more possible solutions exist, some of which you...

Unfortunately, the HTTP 500 internal server error message is agonizingly unhelpful; it's a generalized, catch-all that mostly indicates that the problem can't be more accurately categorized as a different, more specific error.

This internal server error points to a general problem that affects all users and has to be fixed by the website's administrator. On rare occasions, it might be a problem that might affect a single user and can be solved by them.  

What is a 500 internal server error?

The HTTP 500 internal server error is a general-purpose error code that means there is a problem on the website's server, but the exact problem couldn't be definitively identified. In other words, the server doesn't know what the exact problem is. 

This 500 error code can appear in a number of ways, but in most cases the error will either include the code 500, the phrase "internal server error," or both. Because this error is part of the HTTP specification for websites, it can appear in any web browser and any kind of computer, including on mobile devices. 

500 internal server error causes 

Because the 500 error is non-specific, it can take a little detective work to understand what is happening. In general, you can classify this as a problem with the website server's software or configuration, such as one of these issues:

• Permissions issues. Software might be blocked from doing its job because permissions are misconfigured.
• Third-party software, plug-ins or extensions are not working correctly. This is especially likely if a plug-in was recently added that conflicts with other software, or an update means the system is now incompatible with an older plug-in. 
• Other configuration issues. For example, the htaccess file is corrupted or the PHP memory limit has been exceeded. 

How to get rid of a 500 internal server error on a website you're visiting

In general, only the website administrator can solve most 500 errors because they are rooted in the software on the server. But sometimes, the problem can be at the user's end of the connection. If you run into a 500 internal server error, you might want to try a few troubleshooting steps to see if the problem can be resolved.

• Close the browser or restart your computer. This is relatively easy to try, so it should be your first line of troubleshooting: Close the web browser and then restart it to see if that solves the problem. You can also turn the computer off and back on again as well.
• See if the site is down. Visit Downdetector and search for the website to see if it's online. Downdetector doesn't track smaller websites, so you can also try Down.com or Down for Everyone or Just Me. 
• Wait a while. Because the 500 error is almost certainly taking place at the website's server, you can assume the website administrator is working to resolve the problem. If it's a large, popular website, odds are good that technicians are scrambling to resolve the problem as quickly as possible; a smaller website might take longer. Either way, wait a few minutes (or hours) and try again. 
• Delete your cache and cookies. If the site appears to be up but you can't reach it, try to clear your browser cache and cookies. 

How to fix 500 internal server errors on your own website

If your website is displaying 500 internal server errors, you clearly need to take action. There are a handful of things you can try to troubleshoot your problem:

• Deactivate plug-ins, extensions, and themes. The single most likely non-specific problem with your server is likely to be an incompatibility with a recently installed plug-in or add-on, including a webpage theme. In addition, if your server recently installed any software updates, the updated software might now be incompatible with an older plug-in. The remedy: disable all your plug-ins and see if that resolves the issue. If it does, you can selectively enable them one at a time until you find the culprit.  
• Check for recently installed or updated software. Any recent changes are the most likely culprits, and if you've recently installed system or software updates, you might have introduced an incompatibility into your website server. 
• Check for permissions errors. 500 errors are often the result of software not having the proper access. You should check PHP scripts and make sure that permissions are set appropriately. 
• Check your htaccess file. In some cases, the htaccess file can be corrupted or malformed. Make sure it's properly structured.