What is your website?
Have you checked error logs?

Website is http://bucksbearden.com/blog1.php and the error log inside the root directory has the same entry over and over:

[04-Jun-2012 20:22:27] PHP Warning: Unknown: POST Content-Length of 181 bytes exceeds the limit of -2147483648 bytes in Unknown on line 0

The error log inside the htsrv folder says:

[04-Jun-2012 21:43:30] PHP Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 17280 bytes) in /home/bbwdg/public_html/bucksbearden.com/inc/files/model/_image.funcs.php on line 182

The error is probably not related to _evocache issue, but who knows... try to fix it first.
http://stackoverflow.com/questions/6315358/php-warning-post-content-length-of-113-bytes-exceeds-the-limit-of-1988100096-b

Also open the Tools > System tab and examine all warnings.

I used the example of two GB minus one byte and it's still giving the same error.

I checked the system folder and the only thing it's complaining about is the fact my install folder hasn't been deleted. Everything else is in the green.

Have you edited any files in /inc directory? Please set debug password in /conf/_advanced.php and PM it to me

If I PM you will I have to pay you? Just going by what's in your signature.

Not at all

I found and fixed the problem. As I was setting the debug password in /conf/_advanced.php, I found this:

// If you get blank pages, PHP may be crashing because it doesn't have enough memory.
// The default is 8 MB (in PHP < 5.2) and 128 MB (in PHP > 5.2)
// Try uncommmenting the following line:
// ini_set( 'memory_limit', '32M' );

I uncommented the line and changed the limit to 2048M (2GB) and it is writing all specified sizes of thumbnails again. The introductory statement needs to say "If you get blank pages, or missing thumbnail images, PHP may be crashing because it doesn't have enough memory."

This is the missing thumbnail fix everyone has been looking for!

Do you upload 12mpx images straight from camera? In my experience 512Mb is more than enough.

Anyway, good to know you found a fix.

My users either upload directly from their cameras or hard drives, but either way I set it to 2GB just in case some of my users has cameras that approach 20MP. I was trying to test my settings with a 14MP image.

But my question is, why couldn't b2evo 4.1.x be satisfied with the memory limit as specified in the root php.ini file?

That means they simply don't work. The limit you see in Tools > System is the actual number used by b2evo.

That's the thing that confuses me. Although I was seeing a 2048MB limit in Tools > System, my thumbnails were still missing. I didn't get thumbnails until I changed it to 2048MB in /conf/_advanced.php.