Unable to access MailEnable webmail on Plesk server: The requested resource is not found

Symptoms

• Accessing MailEnable webmail shows the following error:
  

  CONFIG_TEXT: Not Found HTTP Error 404.
  The requested resource is not found.

• Also, attempting to access webmail in a browser  may results in blank page loading forever.
• Unable to access MailEnable webmail at http://mewebmail.localhost/. The following error is shown:

  PLESK_INFO: HTTP Error 500.19 - Internal Server Error
  The requested page cannot be accessed because the related configuration data for the page is invalid.
  Detailed Error Information:
  Module AnonymousAuthenticationModule
  Notification AuthenticateRequest
  Handler ExtensionlessUrlHandler-ISAPI-4.0_64bit
  Error Code 0x8007000d
  Config Error Failed to decrypt attribute 'password'
  Config File \\?\C:\inetpub\temp\apppools\MailEnableAppPool\MailEnableAppPool.config
  Requested URL http://mewebmail.localhost:80/
  Physical Path C:\Program Files (x86)\Plesk\Mail Servers\Mail Enable\Bin\NetWebMail Logon Method Not yet determined Logon User Not yet determined Config

Cause

MailEnable webmail IIS site misconfiguration.

Resolution

1. Log in to the server via RDP .

   Note: if direct RDP access to the server is not possible, contact server administrator for further assistance.

2. Launch   C:\Program Files (x86)\Mail Enable\Bin\MEInstaller.exe utility.
3. Execute actions 2(Web application reconfigure), 9(Repair Configuration Files) and 13(Set .NET Framework version for web applications).
   

   Note: MEInstaller.exe will ask for a password. Specify a password that satisfies the Windows complexity requirements, because this is an IIS user password (if not complex enough, it will not be accepted and the corresponding system users will not be created and updated).

4. Restart MailEnable WebMail site under IIS > Sites: