On launching Acrobat, you are prompted to sign in. While signing in, the below error message is displayed, especially when Trend Micro antivirus version 15.0 or earlier is installed and activated on your computer.
Cause: The error occurs with older versions (15 or earlier) of Trend Micro as they restrict certain operations performed by Adobe Acrobat’s protected mode.
To fix the error, try the solutions in the order they appear below:
Solution 1: Update Trend Micro to version 16 or later
Update Trend Micro antivirus to version 16 or later. You can update Trend Micro from within its UI or from the website https://www.trendmicro.com.
Solution 2: Add Acrobat as a trusted application in Trend Micro.
If updating Trend Micro does not work, add the location of the Acrobat application's executable file in the exception list or trusted application list of Trend Micro antivirus. Follow the steps below.
Open the Trend Micro antivirus software.
Click Open The Main Console, and then click Device.
3. To modify the Security Settings, click Configure.
4. In the Protection Settings window, click Exception Lists.
5. Click Add. In the Add an item pop-up dialog,browse to the folder containing the Acrobat.exe file, and then click OK.