In your whole experience of the internet, there are not many things that would annoy you as much as the dreaded 503 error.
Yes, it disrupts your flow when you are using the internet for some entertainment and in some of the most critical situations where you might be presenting a serious topic or doing extensive research on a topic for the class.
You need to keep in mind that this error message is not the same as the 502 bad gateway, although both of them do a similar job of disrupting your work and being troublesome to trace the cause of, especially for the average user.
When you try to solve the 503 error all by yourself, naturally the first thing that comes to mind is to reload the page and sometimes it does work. But, there are times when reloading doesn't help with it, on such occasions, there are certain things that you can do.
When your browser is prevented by something from accessing the target website's server, that is when the 503 error message is shown by the browser. Although the cause of this would not be very obvious, in a general sense you can understand that your server has been unable to handle the information request.
Along with the error, you will also get a handful of suggested fixes to remedy the situation, but one of these is just to try and access the website later.
It is very difficult to gauge the cause of a 503 error, but mostly it's shown when there is something wrong with the server supporting the website that you are trying to access.
There could be a breakdown in the communication between the website and its server, thus making the website unable to handle any user requests for information. This could be caused by anything, it could be some unforeseen technical issue or scheduled server maintenance. If it is the former, you would notice that some of the websites are down more regularly than others, which is generally a sign of the inadequacy of their hosting provider.
The 503 error could also be shown when the traffic on the website is very high, i.e. if the online server doesn't have enough capacity to support the number of requests hitting a website. Such websites do not generally have very high traffic and thus break down or are overwhelmed by the larger audience.
Sometimes the error 503 could also be caused by misconfigured web apps, much like the plugin conflict caused by WordPress.
If the 503 errors are very regular, it could suggest some issue with the Domain Name System (DNS).
To get the site back online, it is very important that the cause of the problem is figured out first.
The first and the fastest method that could help you in the situation of error 503, is reloading the page and hoping that the problem will be solved. But there are various other measures that you can take to make sure that the problem isn't with your connection.
For instance, if you restart your computer or your router and an error message appears saying "Service Unavailable – DNS Failure", then you can take a shy of relief because the problem is at your end and it can be easily corrected by performing a reboot. You could just choose to use a different DNS server if there is a problem with the allocated DNS server.
But, if it is found that the problem is more on the server's side, then there isn't much that you can do from your end to take care of it.
It then becomes a problem for the IP administrator of the website to troubleshoot the issue and find a solution to the HTTP 503 errors encountered by the users. If you are in a position like that and find that the site needs to be updated, you should make sure that you run the updates at a time when the website's traffic is the lowest, so that the users are not disrupted by errors again and again.
Also, if you see that a regular increase in the traffic is causing the error 503, you need to take this as a sign that the web server resources investment has to be boosted.
Finally, if the HTTP 503 has been caused by a programming bug, then you have to dig deeper to pinpoint the issue and rectify it permanently.