Causes of Origin Server Returning Error 503 and How to Fix it?

Hi Guys!

To optimise the speed of my website, I click on the “Speed” tab in the left sidebar of the CF control panel. It shows me the following note:

The speed test could not be run since (my website) returned an Error 503.

Please refer to the screenshot attached.

What is the possible reason behind it?

All known bots are set to “Allow.”

But how to figure out if the configuration between your origin server and Cloudflare is alright and how to ensure that the origin resolves requests successfully?

Please help!


I am sorry to hear you are experiencing an issue with the Speed test.

May I suggest looking into the below article for troubleshooting and resoloving this:

When I access it now, I got Redirect loops error shown:

I am not sure the cause of this, but before moving to Cloudflare, was your Website working over HTTPS connection?

Using Cloudflare Diagnostics Center tool to check:

It says has_redirect_loop -> Yes, your request resulted in a redirect loop.

May I ask what SSL option have you got selected under the SSL/TLS tab at Cloudflare dashboard for your domain ( Flexible, Full, Full Strict … )?


Thank you, Fritex- I am reconnecting the site and will consider your suggestions.

So, if the origin server is also running SSL, is it better to set the SSL setting to full?

My current host also has SSL, so which is the best SSL setting for it?

Other than flexible, - Full or Strict?

Many thanks,

You should choose Full (strict) for maximum security!

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