Showing 404 when tested with GTmetrix

Did you misconfigure the plugin?
Did you ask for support regarding the plugin?
What caching modules are you running?
What is the website URL?

This thread isn’t really helpful to solving your problem.

Agreed with @destac..you are being way too vague. Need more info.

Does the 404s only occur when you test on GTmetrix? On Canadian test servers, but not European? So many more questions.

I agree, I was vague. I guess I’m just annoyed that the plugin author hasn’t provided any answers/support for a long time. In my eyes this plugin is slowly decaying.
Yes, this problem occurs mainly on GTmetrix Canada location. If I run test on Pingdom via US servers, many of the tests go okay but eventually I’ll get 404. Again, that has never happened before. My main audience is in the same country that my server is located, so no problem there, all good.

To answer your questions Destac

Did you misconfigure the plugin?
No changes to plugin setting has been made for over a year.

Did you ask for support regarding the plugin?
Answered above.

What caching modules are you running?
Page cache: disk enhanced
Minify: not in use
Database: Opocode:XCache
Object: Opocode:XCache
Browser cache: enabled
No CDN
All settings are a combination of theme authors suggestions with tweaks fo my setup suggested by my host, and they have served me well. I have applied the PHP7 correction that Kimberly has shared on this forum earlier.

Site is running on shared server Apache CGI/FastCGI. PHP 7.0.4, MySQL 5.6.15, WP 4.5.1.

What is the website URL?
https://www.rar.fi

Any insight that you might provide is greatly appreciated.

In the page cache settings disable the caching of 404 pages.

*uncheck the box*

Thank you, Destac.

I did that, cleared all caches, but it didn’t help. Still 404.

Only your homepage is returning the 404.
https://gtmetrix.com/reports/www.rar.fi/VsWZ4Zkz

This means that its likely one of two things.

1. The cache for W3TC is being messed around with on the homepage.
A. Check to see if you are using edge mode or standard mode. (double check to make sure W3TC is enabled for the homepage.
B. You could enable Debug mode to check as well

2. There is a particular element on the homepage that is causing this.
A. Check the htaccess for anything strange.
B. Make sure to solve the google maps warning.

Google maps require an API key or it gives a warning. That is essentially the only difference between the homepage and the other page. There is also some bad code for instance the
tag is closed like this
not this </br>
https://validator.w3.org/nu/?doc=http%3A%2F%2Fwww.rar.fi%2F

Thank you again Destac. The symptom is gone.

It turns out that over a year ago I added a Twitter feed to the front page. W3TC was interfering with feed updates so I disabled it from the front page, and so has it been ever since. Later I removed the feed but never remembered to change the cache settings back. Still, when looking at the source code, it has shown that caching is working on front page. Curious.

Still this doesn’t explain the fact that the error occured only after the WP update. Something must have triggered it since there were no errors if W3TC was disabled. The underlying cause is a mystery to me.

Answer to your question: No, I have never used the edge mode, and yes I will look into the api key warning, etc.

So, thank you. Could I buy you a beer/coffee via PayPal?

That’s not needed my friend ^^

Okay then. Marking this as resolved.