Redmine

Hi All

We have started experiencing issues while logging into local redmine server hosted on Win server 2012R2 with apache24. The redmine is configured to use LDAP authentication. The login page return 500 error when using Active Directory credentials, but no issues when using local redmine admin account.

The error on the browser:
Proxy Error
The proxy server received an invalid response from an upstream server.
The proxy server could not handle the request POST /login.
Reason: Error reading from remote server

Our Redmine Environment:
Redmine version 3.2.0.stable
Ruby version 2.2.4-p230 (2015-12-16) [x64-mingw32]
Rails version 4.2.5
Environment production
Database adapter Mysql2
SCM:
Filesystem
Redmine plugins:
no plugin installed

The log
Started GET "/" for 127.0.0.1 at 2016-09-23 14:57:10 +0000
Processing by WelcomeController#index as HTML
Current user: anonymous
Rendered news/_news.html.erb (0.0ms)
Rendered welcome/index.html.erb within layouts/base (31.2ms)
Completed 200 OK in 94ms (Views: 56.0ms | ActiveRecord: 15.6ms)
Started GET "/" for 127.0.0.1 at 2016-09-23 14:57:15 +0000
Processing by WelcomeController#index as HTML
Current user: anonymous
Rendered news/_news.html.erb (0.0ms)
Rendered welcome/index.html.erb within layouts/base (15.6ms)
Completed 200 OK in 47ms (Views: 20.9ms | ActiveRecord: 15.6ms)
Started GET "/login" for 127.0.0.1 at 2016-09-23 14:57:17 +0000
Processing by AccountController#login as HTML
Current user: anonymous
Rendered account/login.html.erb within layouts/base (0.0ms)
Completed 200 OK in 16ms (Views: 11.5ms | ActiveRecord: 0.0ms)
Started POST "/login" for 127.0.0.1 at 2016-09-23 14:57:21 +0000
Processing by AccountController#login as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"zjrjx8ofEVMOte9/fm0cK5oekJfqhwI0NAqrxG6hwLWHJWT1KIt6S7n68vv//f2Jz957Kd3jhUSpa/68EdQyaA==", "back_url"=>"http://pe-ap06-ukpar/", "username"=>"nzm8nm", "password"=>"[FILTERED]", "login"=>"Login »"}
Current user: anonymous
An error occured when authenticating nzm8nm: execution expired
Rendered common/error.html.erb within layouts/base (0.0ms)
Completed 500 Internal Server Error in 64531ms (Views: 11.5ms | ActiveRecord: 0.0ms)