Possible cause:
The service account configured in the Domain Settings of ADManager Plus could have expired, be disabled/locked out, or the credentials provided might be wrong.
Resolution:
- Log in to ADManager Plus as the administrator
- Navigate to Domain Settings at the home page's top right corner
- Click on the Edit button next to the Domain you wish to edit.
- You can either change the account provided there or update the password for the existing account.
- Click Update.
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- Click the refresh option on the left, select all objects and click OK.
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- Once a blue pop-up confirms that the product has started to refresh the domain settings, wait for a few minutes for the process to complete.