I deleted Kaspersky antivirus and it all worked.
yes you're right, i fixed it yesterday
Kaspersky was the cause, i didn't delete it, just disabled its "Inject script into web traffic to interact with web pages" from the Network settings
the fix is:
1) Kaspersky Settings > Network settings > disable "Inject script into web traffic to interact with web pages" from the
2) Clear cache in the browser
3) You may have to reinstall construct 3 in the process and clear cache
4) export your apk and enjoy
now everything works normally, with webgl enabled even.
Ashley this is most likely the solution to the error message "The connection to the server was unsuccessful. (file:///android_asset/www/index.html)". antiviruses injecting scripts
same bugs in Github bug reports: #1337 #865 #854 #842 and other forum bug reports