Cloud Front 504 error - The request could not be satisfied

Question

Hi all,

Previously my wordpress website was working correctly with ELB, Cloudfront, S3 in AWS.
However, it was not working suddenly a few days ago and returns "504 ERROR. The request could not be satisfied."

After that, I created a simple page coming_soon.html and it can be accessed www.example.com/coming_soon.html successfully (using the following behavior)
![default](/media/postImages/original/IMC9oU3r57QAmVNpeFIG63Xw)

However, when i added a new behavior for coming_soon.html, it cannot be displayed and return 504.
![coming_soon](/media/postImages/original/IMd-xh8wR_SQmZWHCfy0nVsg)

And I checked the ELB logs, i cannot see any "coming_soon.html" request. It looks like cloudfront drop the request.

Anyone can help? or give me a hits to resolve it?

Thanks
Wayne

NARRAVULA MUNI SAI TEJA · Answer

Hello Wayn...!,

504 error in your CloudFront points to an issue with CloudFront reaching WordPress.

* **Check server access:** Ensure your WordPress server is reachable publicly **(use nc -zv command)**.
* **Verify security groups:** Make sure security groups allow CloudFront IP addresses **on port 80/443** (depending on your setup).

**Check CloudFront settings for `coming_soon.html:`**

**Is path correct?**  : Make sure it points to the exact location of the file on your server.

**Is caching disabled?**  : Set **"Cache Policy"** to **"Caching Disabled"** to see the latest version.

wayne · Answer

@Riku_Kobayashi

Thank for your answer. It works if add "/" at the beginning.

Now, I want to no cache for this page, so i changed to the behaviour as the following (All TTL to be zero). But it doesn't work again (appear 504 again)
![Enter image description here](/media/postImages/original/IMjD16KJNPQ8KwSrIEb5GI7g)

Any ideas?

Thanks

wayne · Answer

Hi everyone,

Thanks for your guys helping first, and sorry for my poor english.

According to the suggestions, I created a new simple php page which just say halo and display current server time, like this:
![Enter image description here](/media/postImages/original/IMMai3Oq4kRdSJGCeuVKJf9Q)

Then I tested 3 cache behavior setting one by one:

**Setting 1:**
Set Default TTL: 120 which makes the page cached 120 sec:

[behavior-setting-01](http://www.loooooops.com/cloudfront_screens/behavior-setting-01.jpg)

**Setting 1 result:**
It works, the page display in expected and the displayed time will be refreshed after reloading after 2 mins later

[behavior-setting-01-result](http://www.loooooops.com/cloudfront_screens/behavior-setting-01-result.jpg)

**Setting 2:**
Set Default TTL: 0:

[behavior-setting-02](http://www.loooooops.com/cloudfront_screens/behavior-setting-02.jpg)

**Setting 2 result:**
The result becomes very interesting:
load normally in 1st time (x-cache: miss from cloudfront)
show 504 error in 2nd time (x-cache: Error from cloudfront)
load normally in 3rd time (x-cache: miss from cloudfront)
show 504 error in 4th time (x-cache: Error from cloudfront)
...

[behavior-setting-02-result](http://www.loooooops.com/cloudfront_screens/behavior-setting-02-result04.jpg)

**Setting 3:**
Changed all TTL to be zero

[behavior-setting-03](http://www.loooooops.com/cloudfront_screens/behavior-setting-03.jpg)

**Setting 3 result:**
The page shows 504 error every time

[behavior-setting-03-result](http://www.loooooops.com/cloudfront_screens/behavior-setting-03-result.jpg)

After i checked the cloudfront logs & elb logs.
I found there is error "OriginCommError" in cloudfront logs, but cannot find any "halo.php" request in elb logs.

It looks like the cloudfront drop the connection before ELB (cannot make a request to ELB) due to some "unknown reason".

Anyone can help? and give me a hits/guideline?

Sorry for my bad english again.

Thanks
Wayne

Riku_Kobayashi · Answer

Hello.

How about changing the path pattern as follows?  
Try adding a "/" at the beginning.  
```
/coming_soon.html
```

Cloud Front 504 error - The request could not be satisfied

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