Phone POS

When I try accept payment, a message is appeared "Security threat. Overlay the current screen by another application is prohibited. Please close all interfering applications and try again!"

This message occurs due to some culprit applications such as Facebook Messenger, Whatsapp, Viber, Skype, Twilight, Сleaner-master, Drupe or any application that can be an add-on over other applications (i.e. can display something on the screen above all other applications).
Option 1. Just close all applications and then try again. 
Option 2. Uninstall applications such as Clean Master, CCleaner, DU Speed Booster, Go Speed or other applications that are advertised as junk cleaner or mobile device boosters. 
Option 3. Try uninstalling antivirus applications (Eset Nod32 Mobile Security & Antivirus, Kaspersky Internet Security Mobile, etc.).
Option 4. For previously installed applications, you need to disable all permissions that allow to overlay the screen of other applications

  1. Go to "Settings",
  2. select "Apps",
  3. gear icon or,
  4. select Draw Over Other Applications. In different devices (different manufacturers), the name may differ. For example, there may be such options as "Display over other applications" or "Picture in picture". Also, this permission can be found in the "Special Access" section 
  5. disable the screen overlay option for those applications that have it enabled. 
  6. you also need to disable screen overlay permissions for hidden system applications by clicking the "Show system applications" icon, or its equivalent.

Option 5. Go to Settings > Apps > Default Apps > Device assistence app > Analyze on-screen text - disable. In different devices (different manufacturers), the name may differ, but the permission must be disabled for the device assistance app that may to analyze text shown on the screen to provide related content)
Option 6. Turn off all functions (including system ones) related to gesture controls (in some devices, these functions are presented in the "Settings" > "Advanced settings" menu (or the section related to screen settings) > "Full-Screen").
Option 7. Check for updates to the Android operating system for your device and update to the most recent version.

Are you satisfied with the answer?