Page cache won't enable

Hello @awr10e

Would you please enable debug mode and check if any error is shown in that page?

To enable debug mode please edit a line in your wp-config.php:
Change

define('WP_DEBUG', false);

to

define('WP_DEBUG', true);
define('WP_DEBUG_DISPLAY', false);
define('WP_DEBUG_LOG', true);

Now try to save again. If any error generates, there will be a file created called debug.log in wp-content folder. Open that file in any text editor and check what is the latest errors. Let us know how it goes.

Have a good day!

Cheers
Ash

Hello Fytrap

You have to use cpanel file manager or ftp to edit that file. You need to go to public_html directory of your domain and there you will see the file wp-config.php.

If you cpanel file manager, then edit that file, make the changes above and save.

If you use ftp, download the file in your local pc, open the file, make the changes above, save the file and then upload the file using ftp.

Have a good day!

Cheers
Ash

OK, I got a bunch of stuff in the Debug log; anything I should be looking for?
This is the latest entry, right after trying to enable page cache:

[08-Aug-2016 23:54:05 UTC] PHP Notice: add_object_page is deprecated since version 4.5! Use add_menu_page() instead. in /home/holein5/public_html/wp-includes/functions.php on line 3658

I really appreciate the assistance; this is basically what I do for a living.

I deactivated everything, still will not enable. Here is the latest from the debug.log after I tried it again:

[10-Aug-2016 01:20:26 UTC] PHP Notice: add_object_page is deprecated since version 4.5! Use add_menu_page() instead. in /home/holein5/public_html/wp-includes/functions.php on line 3658

Hello Fytrap

Well, I am not quite sure about that, sorry. But the settings varies in different servers based on server configuration. If it works for you with basic method, then it should be fine I think 🙂

Have a good day!

Cheers
Ash

Thanks Kimberly! That worked great. That kicked my GTMetrix score up to 88%!
Here are those results:
Installed: Functionality will work properly.
Not detected: May be installed, but cannot be automatically confirmed.
Ok: Current value is acceptable.
Yes / No: The value was successful detected.

Server Modules & Resources:

Plugin Version: 0.9.4.1
PHP Version: 5.5.38;
Web Server: Apache
FTP functions: Installed (required for Self-hosted (FTP) CDN support)
Multibyte String support: Installed (required for Rackspace Cloud Files support)
cURL extension: Installed (required for Amazon S3, Amazon CloudFront, Rackspace CloudFiles support)
zlib extension: Installed (required for compression support)
Opcode cache: Not installed
Memcache extension: Not installed
HTML Tidy extension: Installed (required for HTML Tidy minifier suppport)
Mime type detection: Installed (Fileinfo) (required for CDN support)
Hash function: Installed (hash) (required for NetDNA / MaxCDN CDN purge support)
Safe mode: Off
Open basedir: Off
zlib output compression: Off
set_time_limit: Available
mod_deflate: Not detected (required for disk enhanced Page Cache and Browser Cache)
mod_env: Not detected (required for disk enhanced Page Cache and Browser Cache)
mod_expires: Not detected (required for disk enhanced Page Cache and Browser Cache)
mod_headers: Not detected (required for disk enhanced Page Cache and Browser Cache)
mod_mime: Not detected (required for disk enhanced Page Cache and Browser Cache)
mod_rewrite: Not detected (required for disk enhanced Page Cache and Browser Cache)
mod_setenvif: Not detected (required for disk enhanced Page Cache and Browser Cache)
Additional Server Modules

New Relic
PHP version: Not supported: 5.5.38. Supported versions are 5.2.x, 5.3.x, 5.4.x.
Operating System: Supported
Web Server: Not Supported. (Apache See NewRelic Requirements page.)
WordPress Resources

/home/holein5/public_html/.htaccess: OK
/home/holein5/public_html/wp-content: OK
/home/holein5/public_html/wp-content/uploads/2016/08: OK
Fancy permalinks: /%year%/%monthnum%/%day%/%postname%/
WP_CACHE define: Defined (true)
URL rewrite: Enabled
Network mode: No