No luck finding a reference to my issue so....
I've installed APC 3.1.9 on my CENTOS 5.8 x86_64 server with WHM 11.32.5, Apache 2.2, PHP 5.3.18.
It appears to be working. With the apc.enable_cli option on the following code works as expected:
$bar = 'BAR';
apc_store('foo', $bar);
var_dump(apc_fetch('foo'));
Output is: string(3) "BAR"
APC was compiled from source and installed as a PHP extension. To eliminate any possible configuration issues I have the bare minimum configuration set in my php.ini file:
[apc]
extension="apc.so"
apc.enabled=1
apc.enable_cli=1
(Note that enable_cli has no effect on my issue either way, 0 or 1)
The problem I am having is after copying the apc.php file from the APC source folder to the root of my web folders and opening apc.php in a browser the server is throwing a 500 error. The really odd thing though is that if I run apc.php from the command line php apc.php I'm seeing the expected result (HTML with cache information, though because it's on the CLI it's very minimal cache info.)
Hopefully that's enough info to help get this sucker resolved!
[edit]
The above test code does not work in browser. It also throws a 500 error.
Apache error log shows:
[Sat Oct 27 08:12:14 2012] [error] [client 174.51.36.143] SoftException in Application.cpp:357: UID of script "/home/eduki/public_html/apc.php" is smaller than min_uid