This article shows what information you should consider including in order to get us started debugging HTTP 503 issues.
Common causes of 503-errors can range from TLS certificate expiration or misconfiguration and network issues or an issue with the origin server or a first byte timeout.
There are multiple common 503-errors that can be viewed in this documentation. Fastly generates some 503-errors but if the origin sends us 503-error, we will bypass it back to the clients.
It is a good practice to send the request to origin to determine where the 503-error has been generated. You can easily achieve that by using hosts file and add the origin IP for the domain. You can also use resolve option format --resolve [domain]:[port]:[IP] on cURL.
I would like to share a note about what you can do when a 503-issue arises:
- First check if it can be replicated and assess the urgency of the issue.
- Determine the urgency by reviewing the stats page. If there is a steep elevation of 503s on production, and it has not been resolved, treat it as URGENT.
- The next task is determining where the 503s are coming from. You can send a request to origin directly and see if you can observe the same 503 issue. If it’s successfully replicated, go and investigate the origin otherwise let us know how you investigated.
- If you get blocked on any of the steps, do not worry, open a support ticket to Fastly.
Just like an example observation above, some cases require immediate attention. Relevant information helps to determine how urgent it is and where we can start debugging the issue.
Here is a list of 5 things that can help us to get on your case!
Sending us any keys or tokens would be a very bad move, please remove them from your message.
Where do you see the 503-error?
Is it something you see in your environment? If so was it on the browser or on cURL command output? If it is a customer-reported 503-error, the number of reported cases would be helpful as well.
- When did it start and is it still ongoing?
What is the URL?
If it is not on a specific URL and happening on the account level or service level, please include Customer ID (Account ID) or Service ID.
- What are the steps to replicate it?
Please provide us any additional information that may help us to debug your case. Especially if we cannot replicate, we will need to see the data to understand the nature of the 503s. Logs, command return and screenshots are very helpful
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