Whenever you try to take a screenshot of a WhatsApp View Once message, WhatsApp displays a "This app doesn't allow taking screenshots" error message. Follow the below steps to take a "WhatsApp view once message screenshot":
- Firstly, download and install the TaiChi and DisableFlagSecure apps.
 - Then open the TaiChi app and click on the Float button>create app>create button.
 - After that, install the modified version of the app.
 - Next, go to the module section and activate the DisableFlagSecure module.
 
That's it. Now error message "This app doesn't allow taking screenshots" will not display on the screen.