Why am I seeing ERR_CLEARTXT_NOT_PERMITTED on my Android device?
If you attempt to open a webpage using the in-app mobile browser of the LastPass app for Android, it means that you are navigating to the site using HTTP instead of HTTPS protocol. As a security measure, LastPass does not support initial pageload for HTTP sites, which is the root cause of this error message.
If you would like to proceed and the site supports HTTPS, you can manually change the HTTP to HTTPS in the address bar of the LastPass in-app mobile browser and navigate to the site again to load the webpage. If this site is stored in your LastPass vault and you plan on launching it in the future, you can edit the site entry and change the HTTP to HTTPS so that you no longer encounter the error for that site.