Return of 502- Bad gateway Error

[SeanB]

Refresh would force a reload, and generally a transient overload on the server, which caused the original failure, will be gone. However, the continuing reloads only add to the load on the server.

A much better thing instead is to stop, get up from your device, and go either have a drink of water, a short walk around outside, or something else that does not involve going to the website. This serves many functions. Firstly you are not adding to the load on the single site, so the backlog will be done, and the next time you come there, a few minutes later, you will be successful. Second it gets you off your backside, and moving about a little, alleviating the risk of DVT and at a least getting your circulation going better. The drink of water will hydrate you as well, and if you go for a short walk it will clear your brain.

Note none of this has any cost, and also is going to both relax you, be good for your general well being and help you in reducing stress in your life.

[jpanhalt]

Refresh would force a reload, and generally a transient overload on the server, which caused the original failure, will be gone. However, the continuing reloads only add to the load on the server.

A much better thing instead is to stop, get up from your device, and go either have a drink of water, a short walk around outside, or something else that does not involve going to the website. This serves many functions. Firstly you are not adding to the load on the single site, so the backlog will be done, and the next time you come there, a few minutes later, you will be successful. Second it gets you off your backside, and moving about a little, alleviating the risk of DVT and at a least getting your circulation going better. The drink of water will hydrate you as well, and if you go for a short walk it will clear your brain.

Note none of this has any cost, and also is going to both relax you, be good for your general well being and help you in reducing stress in your life.

Neglecting your smartass advice and addressing your content...

It seems clear you don't know the reason for the error, as your suggested solution simply didn't work.   First time it happened to me, I tried accessing over two days, including at least one complete shutdown of my system.  Although I had not had that exact error before, my assumption was something at the server, which for most sites that I visit is fixed within a few hours.  I then cleared my shortcut and re-entered the URL.   That worked. 

Next time it happened, I did a very quick search on Google, found the refresh option in a stackexchange thread on the very subject, and have been using that option since. 

As best I can tell, this problem on eevblog was first reported in 2014 (https://www.eevblog.com/forum/chat/%27recent-posts%27-502-bad-gateway-error/ ).  That and several related threads have had no response from administration.   As they say, if you are not part of the solution, you are part of the problem.

John

[SeanB]

Neglecting your smartass advice and addressing your content...

It seems clear you don't know the reason for the error, as your suggested solution simply didn't work.   First time it happened to me, I tried accessing over two days, including at least one complete shutdown of my system.  Although I had not had that exact error before, my assumption was something at the server, which for most sites that I visit is fixed within a few hours.  I then cleared my shortcut and re-entered the URL.   That worked. 

Next time it happened, I did a very quick search on Google, found the refresh option in a stackexchange thread on the very subject, and have been using that option since. 

As best I can tell, this problem on eevblog was first reported in 2014 (https://www.eevblog.com/forum/chat/%27recent-posts%27-502-bad-gateway-error/ ).  That and several related threads have had no response from administration.   As they say, if you are not part of the solution, you are part of the problem.

John

Does work for me though.

[PA0PBZ]

What seems to be going on and where the confusion comes from I think is the following:
Whenever I get/got this 502 error it always takes some time before it shows up, but then when I go back and click the link again the error shows up instantly, so my guess is that the error gets cached somehow. You can click the link 10 times if you want and the error stays, but one time <Ctrl-F5> will clear it. So I don't care how many people say that it doesn't work, it works for me and I'm not the only one.

[tooki]

OK, I see where you're coming from.

Just to make sure we're on the same page, we know that the error itself is a server-side problem.

I guess the link in the error page causes the browser to use its cache. So when the server-side problem resolves itself, the browser isn't even attempting to reload.

Force refreshing doesn't make the server-side problem go away, but in fact exacerbates it. But without a refresh, your browser will continue to show the error message instead of the page (at least, until the expiration time of the cached page elapses.) So we've got the issue where refreshing actually delays the root issue being fixed, but is nonetheless necessary for the user-facing problem to go away.

I've normally simply walked away when I've gotten the error, done something else, and 5 minutes later it works. That's unwittingly given the server enough time to catch its breath, at which point the refresh succeeds.

[tautech]

To add to others experience and mentioned before, Unread Replies link might not work but immediately removing the forward slash from the URL does. Thereafter refreshing the page works without incident indefinitely but using the link again produces errors again no matter how long one waits.
I've had same problem with the main forum page off and on for a year or more, again tweaking the URL by removing .php gets it working without exception.
It's typical to need multiple tabs open to be able to use the forum and keep up to date.

[Monkeh]

To add to others experience and mentioned before, Unread Replies link might not work but immediately removing the forward slash from the URL does. Thereafter refreshing the page works without incident indefinitely but using the link again produces errors again no matter how long one waits.
I've had same problem with the main forum page off and on for a year or more, again tweaking the URL by removing .php gets it working without exception.
It's typical to need multiple tabs open to be able to use the forum and keep up to date.

This seems far more likely to be your browser being exceedingly badly behaved. That or your ISP is running a really, really broken caching proxy.

[Monkeh]

How about Cloudflare being the broken caching proxy?

If that were the case there'd be more than one or two people reporting such substantial issues. I'm no fan of Cloudflare, but they're not to blame here. Just for a dozen other things.

[hendorog]

OK, I see where you're coming from.

Just to make sure we're on the same page, we know that the error itself is a server-side problem.

I guess the link in the error page causes the browser to use its cache. So when the server-side problem resolves itself, the browser isn't even attempting to reload.

Force refreshing doesn't make the server-side problem go away, but in fact exacerbates it. But without a refresh, your browser will continue to show the error message instead of the page (at least, until the expiration time of the cached page elapses.) So we've got the issue where refreshing actually delays the root issue being fixed, but is nonetheless necessary for the user-facing problem to go away.

^^^ This.

The browser is caching the error page for days without a force refresh - I just cleared the Database Maintenance error message dated 24th March with a forced refresh.

[tooki]

But that's weird. It shouldn't stay cached for anywhere near that long! (And on my computers/devices, it doesn't.)

[jpanhalt]

But that's weird. It shouldn't stay cached for anywhere near that long! (And on my computers/devices, it doesn't.)

Shouldn't, wouldn't, couldn't ...

I have heard that too many times to count.   In my business, such theories didn't hold a candle to what actually happens.  I know of at least one IT "expert" who got fired because he didn't understand that difference.

If this blog wants to be PC-specific, then it needs to tell us what we need to do to get access.  Otherwise, it needs to be robust enough to work with many platforms, including at least Windows and Chrome.

John

[xrunner]

Man this error is really bad here this evening. Not sure why ... 

[StillTrying]

But that's weird. It shouldn't stay cached for anywhere near that long! (And on my computers/devices, it doesn't.)

There's some strange caching going on now that wasn't before.
'Shift-Reload'.

[xrunner]

I just got a "524 Error"

I tried to get a screen capture but failed. I'll try next time.

[bktemp]

I just got a "524 Error"

I had one too yesterday. It was the first time I had seen this error on the forum.
First it took a long time loading the page (maybe 30s) then the 524 timeout error showed up (it was from cloudflare). After pressing F5 it turned into the 502 error page. Pressing F5 again finally loaded the page but very slowly (>10s).
It looks like there is still something wrong and occasionally the server is busy servicing all the requests.

[tautech]

To add to others experience and mentioned before, Unread Replies link might not work but immediately removing the forward slash from the URL does. Thereafter refreshing the page works without incident indefinitely but using the link again produces errors again no matter how long one waits.
I've had same problem with the main forum page off and on for a year or more, again tweaking the URL by removing .php gets it working without exception.
It's typical to need multiple tabs open to be able to use the forum and keep up to date.

This seems far more likely to be your browser being exceedingly badly behaved. That or your ISP is running a really, really broken caching proxy.

I've often wondered the same but no other websites repeatedly throw errors like the forum does.
Chrome, latest version and Win 7 64 bit.

I consistently have ~20 tabs open as I have slow internet and it's simpler/faster to refresh those I work with than reopen them.

[hendorog]

To add to others experience and mentioned before, Unread Replies link might not work but immediately removing the forward slash from the URL does. Thereafter refreshing the page works without incident indefinitely but using the link again produces errors again no matter how long one waits.
I've had same problem with the main forum page off and on for a year or more, again tweaking the URL by removing .php gets it working without exception.
It's typical to need multiple tabs open to be able to use the forum and keep up to date.

This seems far more likely to be your browser being exceedingly badly behaved. That or your ISP is running a really, really broken caching proxy.

Actually I'd say this is just an artifact of the way the forum servers are setup. The cached error page is associated with the URL you requested with the slash on the end. Removing the slash is seen as a different request and so the cache is ignored and hits the server. This particular proxy/server/app combo doesn't care about whether the slash is there or not and so serves up the same page.

Same thing happens when you remove the .php. The server still serves the page with or without the .php, but the cache in the browser sees it as a different request.

i.e. These all go to the same page:
https://www.eevblog.com/forum/index
https://www.eevblog.com/forum/index.php
https://www.eevblog.com/forum/

[tooki]

But that's weird. It shouldn't stay cached for anywhere near that long! (And on my computers/devices, it doesn't.)

Shouldn't, wouldn't, couldn't ...

I have heard that too many times to count.   In my business, such theories didn't hold a candle to what actually happens.  I know of at least one IT "expert" who got fired because he didn't understand that difference.

Oy gevalt, uppity much?

I said it shouldn't, not that it wasn't. The entire implication of my comment was that it's strange that you're experiencing that behavior. Ergo, something to look into.

As for someone getting fired, that's meaningless, in that people are often fired as scapegoats for something they really weren't responsible for.

If this blog wants to be PC-specific, then it needs to tell us what we need to do to get access.  Otherwise, it needs to be robust enough to work with many platforms, including at least Windows and Chrome.

What on earth is this rant about?

[RoGeorge]

How does a server distinguish between a page request coming from the link "Show unread posts since last visit." (the one on the top of each page, near the user's avatar) versus the same address, "https://www.eevblog.com/forum/unread/", coming from a refresh (F5) action?

I am asking this because:
- before the database maintenance, I had 502 Err here and there, maybe once in a week, and the err goes away by itself at the next access of the same link
- after the database maintenance, the two links near the avatar were ALWAYS returned 502 err for me. I testes it many times, I tried them maybe 20-30 times over a couple of hours. Always 502 Err.
- then, after one F5 for each link, the 502 Err has gone forever. I didn't saw a 502 Err since then.

Of course, this might be just a coincidence, but it's very hard to believe.
The most probable explanation to me is that the server has received a different type of request for the F5, compared with the request coming from the link "https://www.eevblog.com/forum/unread/". That different request, apart from re-sending the page, also permanently fixed the 502 Err.

Seems to me that F5 is sending something else then just the URL from the address bar, or at least is doing something different on the browser side.

So, my curiosity is: What exactly does a browser send/do when I press F5, compared to a simple click on a link, please?

[tooki]

I don't know the exact naming, but an HTTP request does include the "referrer", so a web server really can distinguish a clicked link from a refresh or a manually-entered URL.

[StillTrying]

502s seen on both the 502 threads. LOL

[tkuhmone]

Fyi,

I saw 502 error today at 12:00 GMT. Waited couple of minutes and then try to login at forum again -> works ok...

[EEVblog]

I've had several slowdowns and 524 errors tonight.
The server will be getting a RAM upgrade soon which gnif assures me will help.

[xrunner]

Don't know if any upgrades have been done, but no errors at all today! 

[tautech]

Don't know if any upgrades have been done, but no errors at all today! 

Just checked my Unread Replies link that's returned 502 errors for days and up until a few hours ago, instead of using it I leave a tab open and just refresh it......don't need to do that now. 


Hope I don't have to post in this thread again.