HTTP Error 500 (Internal Server Error) on Config Pages

Check the issue queu, release notes, and documentation. And if you really want help, provide more details than 500 error, which is generic.

I am getting the same thing.

this is the actual error:

The website encountered an error while retrieving http://xxxxx.co.uk/?q=admin%2Fconfig%2Fservices%2Fmailchimp%2Flists%2Fadd&. It may be down for maintenance or configured incorrectly.

This is what the log file says
[31-Jan-2013 20:16:40 America/New_York] PHP Fatal error: Call to undefined function libraries_load() in /####/#####/public_html/#####/sites/all/modules/mailchimp/mailchimp.module on line 200
[31-Jan-2013 20:20:40 America/New_York] PHP Fatal error: Call to undefined function libraries_detect() in /####/####/public_html/#####/sites/all/modules/mailchimp/mailchimp.install on line 43

I just dealt with this too - make sure you read this carefully - http://drupalcode.org/project/mailchimp.git/blob/HEAD:/README.txt

Especially the bit about # Installation Notes

Same error, coming from a long way...

Documentation and issues reviewed:

http://drupal.org/project/mailchimp
http://drupal.org/documentation/modules/mailchimp
/sites/all/modules/mailchimp/README.txt
http://drupal.org/node/1883984
http://drupal.org/node/1894956
http://drupal.org/node/1314268

Currently installed modules and libraries:

Drupal 7.19
Libraries API 7.x-2.0
MailChimp 7.x-2.10

Done and remaining issues:
MCAPI.class.php (MailChimp PHP API Wrapper 1.3) Finally, The MailChimp MCAPI wrapper library is installed correctly.
Deleted /sites/all/modules/mailchimp/includes/mailchimp.inc file and replacing line 201 in mailchimp.module as suggested in #14 in 1314268, still got this 500 error...
API key input in Drupal, but "You have no applications authorized just yet." in Mailchimp Authorized Applications.

Followed #54 of http://drupal.org/node/1883984 step by step exactly again, finally got the "add a list" working...Sam

#1883984: Fix for "Can't get module to recognize library"