Http error 503 service unavailable explained

Tim Fisher has more than 30 years' of professional công nghệ experience. He's been writing about tech for more than two decades và serves as the VP and General Manager of

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The 503 Service Unavailable error is an HTTP status code that means the website"s vps is not available right now. Most of the time, it occurs because the vps is too busy or maintenance is being performed on it.

Are You the web Manager? See the Fixing 503 Errors on Your Own Site section further down the page for some things khổng lồ look at if you're unsure what lớn do.

A 503 error message can be customized by the website it appears on or the server software that generates it, so how you might see it vary greatly.

503 Service Unavailable errors can appear in any browser in any operating system, including Windows 10 back through Windows XP, macOS, Linux, etc...even your điện thoại cảm ứng thông minh or other nontraditional computers. If it has mạng internet access, you could see a 503 in certain situations.

How You Might See the 503 Error

Here are the most common ways you might see the "service unavailable" error:

503 Service Unavailable503 Service Temporarily UnavailableHttp/1.1 Service UnavailableHTTP vps Error 503Service Unavailable - DNS Failure503 ErrorHTTP 503HTTP Error 503Error 503 Service UnavailableError 503 Backend fetch failed

Sites that use Microsoft IIS may provide more specific information about the cause of a 503 Service Unavailable error by suffixing a number after the 503, as in HTTP Error 503.2 - Service Unavailable, which means Concurrent request limit exceeded. See More Ways You Might See a 503 Error near the bottom of the page for the whole list.

How to lớn Fix the 503 Service Unavailable Error

The 503 Service Unavailable error is a server-side error, meaning the problem is usually with the website's server. Your computer may have an issue causing the 503 error, but it's not likely.


Retry the URL from the address bar again by clicking the reload/refresh button or pressing F5 or Ctrl+R.

Even though the 503 Service Unavailable error means there's an error on another computer, the issue is probably only temporary. Sometimes just trying the page again will work.

If the 503 Service Unavailable error message appears while paying for an online purchase, be aware that multiple attempts to kiểm tra out may kết thúc up creating multiple orders và multiple charges. Most payment systems and some credit card companies have protections from this kind of thing, but it's still something you should know.

Restart your router and modem. Then restart your computer or device, especially if you see the Service Unavailable - DNS Failure error.

While the 503 error is still most likely the fault of the trang web you"re visiting, there may be an issue with the DNS server configurations on your router or computer, which a simple restart of both might correct.

If rebooting your equipment didn"t correct the 503 DNS Failure error, there might be temporary issues with the DNS servers themselves. In this case, pick new DNS servers from our không tính phí & Public DNS Serverslist và update the servers on your computer or router.

Another option is to tương tác the website directly for help. There's a good chance that the site's administrators already know about the 503 error, but letting them know, or checking the status on the problem, isn't a bad idea.

Most sites have support-based social network accounts, và some even have phone numbers and email addresses.

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If the trang web giving the 503 error is a popular one, and you think it might be down completely, kiểm tra if the website is down by plugging its URL into a service lượt thích Freshping"s Is it down tool. A smart Twitter search can usually give you the answer, too. Try searching for #websitedown on Twitter, replacing website with the site name, as in #facebookdown or #youtubedown. An outage on a prominent site will usually generate lots of talk on Twitter.

Come back later. Since the 503 Service Unavailable error is a common error message on trendy websites when a massive increase in traffic by visitors is overwhelming the servers, simply waiting it out is often your best bet. Frankly, this is the most likely "fix" for a 503 error. As more và more visitors leave the website, the chances of a successful page load for you increase.

Fixing 503 Errors on Your Own Site

With so many different web server options out there & even more general reasons why your service might be unavailable, there isn't a straightforward "thing to lớn go do" if your site is giving your users a 503.

That said, there are certainly some places lớn start looking for a problem và then hopefully a solution.

Start by taking the message literally—has something crashed? Restart running processes & see if that helps.

Beyond that, look at not-so-obvious places where something might have hiccuped. Where applicable, look at connection limits, bandwidth throttling, overall system resources, fail-safes that might have triggered, etc.

In what's very likely a "double-edged sword" for your website, it may be that it's suddenly very, very popular. Getting more traffic than you built your site lớn handle almost always triggers a 503.

However, the 503 error could also result from a malicious denial of service (DoS) attack. If so, getting into liên hệ with the company hosting your trang web would be wise to discuss steps that you can take to lớn reduce the likelihood of it happening again or khổng lồ better prepare for another in the future.

Even an unintentional DoS attack can occur, where a virut on the server is sucking away usable system resources and slowing the hệ thống down khổng lồ the point that it causes a 503 error.

More Ways You Might See a 503 Error

In Windows applications that inherently access the internet, a 503 error might return with the HTTP_STATUS_SERVICE_UNAVAIL error, và maybe also with a The service is temporarily overloaded message.

Windows Update might also report an HTTP 503 error, but it will display as error code 0x80244022 or with a WU_E_PT_HTTP_STATUS_SERVICE_UNAVAIL message.

Some less common messages include 503 Over QuotaConnection Failed (503), but the troubleshooting above applies all the same.

If the website that reports the 503 error happens khổng lồ be running Microsoft's IIS web hệ thống software, you might get a more specific error message lượt thích one of these:

IIS 503 Errors
Status CodeReason Phrase
503.0Application pool unavailable
503.2Concurrent request limit exceeded
503.3ASP.NET queue full
503.4FastCGI queue full

Errors lượt thích 503 Service Unavailable

The 503 Service Unavailable error is a server-side error. It"s very much related to lớn other server-side errors lượt thích the 500 Internal server Error, the 502 Bad Gateway error, & the 504 Gateway Timeouterror, among others.

Several client-side HTTP status codes exist, too, like the standard 404 Not Found error, among others.