Return of 502- Bad gateway Error

[gnif]

502's don't affect a single page, they are site wide.

Really, there's often only one thread or part of the site, such as the projects index page that we can't get to.

Yes, 502 means that there is an internal server error where the PHP process is not availble for Nginx to communicate with. For those that don't understand the process, this is how an incoming HTTP request is served.

1) Your client establishes a connection with the server (Nginx)
2) Your client asks the server for a resource
3) The server determines if the resource is a static file (ie, image), or dynamic (php script in this instance).
4a) For static the webserver just grabs the file on disk and send's it out.
4b) For dynamic the webserver connects internally to the PHP service on the server and asks it to run the script

502 errors are when the webserver can't connect to a non busy PHP service... the cause can be any number of things, bad script, PHP crashed, MySQL didnt return in a timely manner and all the PHP processes are hung up waiting. etc...

It doesn't matter what page, it doesn't care at this point. It can happen on any page at any time. Unfortunately CF do strange things with caching the 502 error (this likely can be resolved but up till now I have not investigated this aspect of the issue yet).

Because tons of people use the 'show new replies' feature, when we get 502 errors it has a high probability of being cached at cloud flare as broken. CF starts dishing out the static 502 even after the issue has been resolved for that particular page, which is why a force refresh will resolve it as this instructs CloudFlare to go and fetch the content again anyway.

[hermit]

502's don't affect a single page, they are site wide.

Really, there's often only one thread or part of the site, such as the projects index page that we can't get to.

A full 24 hours after "Show unread posts since last visit." started acting correctly " Show new replies to your posts." was still giving me a 502, even after multiple page reloads.  I had to dump my cache, which I though was turned off.

[EEVblog]

How is ping coming throw the captcha question?
If you are not logged in you need to answer a question.

You can read and search this forum without an account. The search bot are not logging in.
I think I can disable the search feature to account holders only, but I don't like doing that.

[glarsson]

The search bot are not logging in.

How does it get past the captcha you are asked to answer when not logged in? I thought the captcha was intended to stop bots.

[Muttley Snickers]

You can read and search this forum without an account. The search bot are not logging in.
I think I can disable the search feature to account holders only, but I don't like doing that.

Generally speaking and just for the record, both members and guests are still able to use Google or similar search engines to find particular topics or threads, I have a tendency to use this rather than use the forums search feature which from my experience can be a bit hit and miss, I don't know why this is, example below.

[gnif]

I am updating the 502 error (still states that we are doing DB updates, lol)... I will also create a thread that it specifically links to for reporting errors.

[tronde]

I think I can disable the search feature to account holders only, but I don't like doing that.

What about a time limit between searches for guests? I have seen some forums using only a few seconds as a limit. After reading here, I guess that is related to bots.

[Muttley Snickers]

I am updating the 502 error (still states that we are doing DB updates, lol)... I will also create a thread that it specifically links to for reporting errors.

This has been discussed before and I don't know why it was not implemented earlier, as you can see we end up with multiple threads discussing the same subject or new threads addressing individual users problems which are sometimes just a profile checkbox tick.   

[gnif]

I think I can disable the search feature to account holders only, but I don't like doing that.

What about a time limit between searches for guests? I have seen some forums using only a few seconds as a limit. After reading here, I guess that is related to bots.

Not sure why this is even being discussed... the problem is resolved, the server is able to handle a massive amount of search load now without any negative impact.

[gnif]

I am updating the 502 error (still states that we are doing DB updates, lol)... I will also create a thread that it specifically links to for reporting errors.

This has been discussed before and I don't know why it was not implemented earlier, as you can see we end up with multiple threads discussing the same subject or new threads addressing individual users problems which are sometimes just a profile checkbox tick.   

The thread will not be for forum usage/profile issues, etc.. it is specifically for server outages. If you want a thread for that kind of support please ask Dave as I do not cover individual user issues, I do not have the time.

[pknoe3lh]

How is ping coming throw the captcha question?
If you are not logged in you need to answer a question.

You can read and search this forum without an account. The search bot are not logging in.
I think I can disable the search feature to account holders only, but I don't like doing that.

Yes I can do that ... But not a robot ;-)
So how can bing use the search box?
Can they solve captchas?

[gnif]

How is ping coming throw the captcha question?
If you are not logged in you need to answer a question.

You can read and search this forum without an account. The search bot are not logging in.
I think I can disable the search feature to account holders only, but I don't like doing that.

Yes I can do that ... But not a robot ;-)
So how can bing use the search box?
Can they solve captchas?

Top right hand corner quick search doesn't require a captcha

Edit: For search engines... it is intentional so that they can index the site.

[eugenenine]

[
So how can bing use the search box?

Why would you want to use a website that can't find anything (bing).  I have to use google to search the MSKB at work now because bing can't find articles that exist.

[pknoe3lh]

The forum Rocks again