500 Internal Server Error when enabling Debug Mode

Resolved Stanislav Khromov
(@khromov)

10 years, 11 months ago

If I enable Debug Mode while Page Cache is enabled, a 500 Internal Server Error occurs when loading the site.

The first pageload shows correctly, but when refreshed, you get the 500 error.

There is nothing in Apache error log.
There are no PHP error messages.
The returned page is just blank.

So far I have tried:
– Reinstalling W3TC
– Disabling all gzip settings.
– Disk and APC page cache.

None of those worked.

I did notice that when debug mode is enabled, gzip versions of the pgcache variable are not generated.

Thanks beforehand.

Edit
I think this is definitely a bug. Downgraded to W3TC 0.9.2.9 and it works just fine on the same settings, no 500 errors.

http://wordpress.org/extend/plugins/w3-total-cache/

Viewing 3 replies - 1 through 3 (of 3 total)

(@_doherty)

I’m seeing this error on my blog’s front page. When W3C is configured to cache the front page in memcached, such requests return a 500 error. If I disable memcached, or configure W3C to not cache the front page, it is served properly. I therefore believe the error is related to memcached.

I started a memcached server with the -vv option to see client commands and server responses. Here’s some example output. 9132ff75232182b4e3b1de9ba6cf6fdc is the front page. I separated HTTP requests with a blank line. The first and second requests work; the third returns an HTTP 500.

<30 new auto-negotiating client connection
30: Client using the ascii protocol
<30 get w3tc_0_pgcache_0_779812058_key_version
>30 END
<30 set w3tc_key_hashbang.ca_0_pgcache_9132ff75232182b4e3b1de9ba6cf6fdc_0 3 3600 15871
>30 STORED

<30 get w3tc_key_hashbang.ca_0_pgcache_9132ff75232182b4e3b1de9ba6cf6fdc_0
>30 sending key w3tc_key_hashbang.ca_0_pgcache_9132ff75232182b4e3b1de9ba6cf6fdc_0
>30 END
<30 get w3tc_0_pgcache_0_779812058_key_version
>30 END
Failed to write, and not due to blocking: Connection reset by peer
<30 connection closed.
<30 new auto-negotiating client connection
30: Client using the ascii protocol
<30 get w3tc_0_pgcache_0_779812058_key_version
>30 END
<30 set w3tc_key_hashbang.ca_0_pgcache_9132ff75232182b4e3b1de9ba6cf6fdc_0 3 3600 15869
>30 STORED
<30 get w3tc_key_hashbang.ca_0_pgcache_9132ff75232182b4e3b1de9ba6cf6fdc_0
>30 sending key w3tc_key_hashbang.ca_0_pgcache_9132ff75232182b4e3b1de9ba6cf6fdc_0
>30 END
<30 get w3tc_0_pgcache_0_779812058_key_version
>30 END

<31 new auto-negotiating client connection
31: Client using the ascii protocol
<31 get w3tc_key_hashbang.ca_0_pgcache_9132ff75232182b4e3b1de9ba6cf6fdc_0
>31 sending key w3tc_key_hashbang.ca_0_pgcache_9132ff75232182b4e3b1de9ba6cf6fdc_0
>31 END
<31 get w3tc_0_pgcache_0_779812058_key_version
>31 END

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