This can happen for a variety of reasons, including thePDF not being correctly decoded during download or its format not being supported by Adobe. However, you do not need to be concerned about Adobe not opening PDF on your Android because there are other solutions available. One of the solutions for adobe not opening pdf on android may be found here.

1. On your mobile phone go to the options menu
2. Select Apps.
3. Locate the Adobe Reader application.
4. Select Force Stop from the drop-down menu.
5. To force a stop, click Okay.
6. Clear cache and clear data are the two options available.
7. Then navigate to the Playstore.
8. Look for Adobe Reader.
9. To update your app, select Update.
10. Your phone should be restarted.