After asking Hengtian hosting support to switch the server’s PHP version, the site at armvs.com stopped loading completely and returned a 503 error:
Service Unavailable
The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.
At first, I found a post suggesting that the issue might be related to a port change:
https://www.fujieace.com/php/503-service-unavailable.html
That was just something I came across through Baidu while trying to narrow down the cause.
Support later replied with the actual error they saw after the site was moved to PHP 7.2:
[Thu Jun 25 10:22:19.917261 2020] [proxy_fcgi:error] [pid 28786:tid 140028751607552] [client 172.68.141.219:30492] AH01079: failed to make connection to backend: httpd-UDS
They switched the account back to PHP 5 so the site could become accessible again, and suggested checking the error log and fixing the site code manually. They also provided a log tutorial:
查看错误日志：http://www.hengtian.cc/archives/90.html
I then went through the error log myself and found the following entries:
[Thu Jun 25 03:56:06.963227 2020] [core:error] [pid 14043:tid 139671463884544] (13)Permission denied: [client 172.69.34.89:42190] AH00035: access to /index.php denied (filesystem path '/home/armvscom/domains') because search permissions are missing on a component of the path
[Thu Jun 25 04:39:46.628090 2020] [core:error] [pid 15205:tid 139671430313728] (13)Permission denied: [client 36.57.179.149:9339] AH00035: access to /index.php denied (filesystem path '/home/armvscom/domains') because search permissions are missing on a component of the path
[Thu Jun 25 08:33:39.870237 2020] [access_compat:error] [pid 12093:tid 139671749236480] [client 37.59.46.228:54863] AH01797: client denied by server configuration: /home/armvscom/domains/armvs.com/public_html/xmlrpc.php, referer: http://www.google.com.hk
[Thu Jun 25 09:20:30.678804 2020] [proxy:error] [pid 10877:tid 140028315186944] (2)No such file or directory: AH02454: FCGI: attempt to connect to Unix domain socket /usr/local/php72/sockets/armvscom.sock (*) failed 粗体部分错误 重复出现。剩下waring 之类的 都不用看了。
The repeated part that really stood out was the socket connection failure. The warnings and other less relevant messages were not the focus at this stage.
While searching for similar cases, I ran into another blog post documenting a comparable WordPress FPM issue:
https://84361749.com/post/errorlog-wordpress-fpm.html
The fix shown there was:
# pool.conf
[wordpress]
listen=/opt/php/var/run/wordpress.sock include=/opt/php/etc/common-dynamic.conf include=/opt/apps/wordpress/conf/php-fpm/php-settings.conf include=/opt/php/etc/environment.conf pm=dynamic
In that example, the second include line had been left pointing to the wrong location. After changing it to the correct path and restarting the server, one more error log issue was resolved.
For now, I’m still checking what needs to be adjusted before the site can safely switch over to PHP 7.2.