Unable to access website on Plesk server with 500 error message: ADODB.Connection error ‘800a0e7a’

Symptoms

• Unable to access example.com domain with the default 500 error message:

  500 external Server Error

• Accessing the domain from Windows server itself shows the below error:

  ADODB.Connection error '800a0e7a'
  The specified provider could not be found. It may not be installed correctly.
  /index.asp, line 43

Cause

Mismatch between the architecture of Windows server, database, and the connection drivers.

Resolution

1. Login to Plesk .
2. Go to Domains > example.com > Hosting & DNS > Dedicated IIS Application Pool for Website page.
3. Enable Enable 32-bit applications option and click OK.
4. If the issue persists, navigate to Tools & Settings > IIS Application Pool page, enable Enable 32-bit applications option and press OK button.