I did a bunch of tracing and finally found that the problem was that the $mcFileManagerConfig['preview.wwwroot'] was in fact what was causing the problem.

Our test server is hosted by Acquia and the way they've setup the server has a bunch of symlinks that point to the correct path. I found out that the path I *thought* was the root path was in fact not by doing a var_dump() in the convertPathToURI() function in MCImageManager\classes\ManagerEngine.php.

Thanks very much for your help! I just finished finding the cause of the problem and fixing it and I see that simply enabling the logging system would probably have shown me the cause a lot quicker. I will keep it in mind down the line.

Once again, thank you very much! Please consider this case solved

Thanks for getting back to me so soon!

I've implemented the following settings; unfortunately, I'm still receiving the exact same error. Please note, I've been making sure to perform a Drupal clear-cache after each change to the module settings.

Here's the path to where MCImageManager is installed:
sites/all/modules/contrib/MCImageManager

Here's the value I've put into preview.wwwroot:
'/var/www/html/majorisdev/docroot'

Here's the configuration of the rootpath/path settings:
$mcImageManagerConfig['filesystem.rootpath'] = '../../../../default/files';
$mcImageManagerConfig['filesystem.path'] = '../../../../default/files';

Hope this helps clarify things further!

Thanks for the support once again!

I just recently bought a license for MCImageManager & MCFileManager. I've been trying to debug a problem that is very confusing. I and another team member have spent a couple hours off and on trying to figure out what is causing this problem.

Notes:
1) It is a Drupal 7 setup.
2) The following is happening on my remote testing server.
3) The modules work perfectly fine on my local laptop environment (Windows 7 / WAMP).
4) In order to get the text editor to load in the first place, I had to modify the "DRUPAL_ROOT" constant in "plugins/DrupalAuthenticator/DrupalAuthenticator.php":

-- FROM: define(DRUPAL_ROOT, MCMANAGER_ABSPATH . "../../../../../");
-- TO: define(DRUPAL_ROOT, MCMANAGER_ABSPATH . "../../../../../../");

Steps:
1) I click on "Insert / Edit Image" and/or "Insert Image"
2) I see images that I've uploaded available in the dialog.
3) I click on the arrow-btn at the bottom right of an image and then choose "Edit"
4) A new dialog loads but the image doesn't appear.
5) I checked the URL that is being called for loading the image in FireBug's "Net" panel and it shows that the URL is malformed... I.e.: instead of being "http://mysite-dev.devdomain.com/sites/default/files/filename.jpg" it is trying to load "http://mysite-dev.devdomain.comefault/files/image-small.jpg?rnd=1328575555000".
6) Please note the lack of the slash and directory names "***.com/sites/default" in the URL above.

Thank you very much for your support and wonderful module/plugin!