After upgrading to OC 10, two factor authorization with the OC 10 app "Two Factor TOTP Provider 0.4.2" stopped working, saying that the app requires a PHP version <= 7.0 This came as a complete surprise to me, because the OC changelog for 10.0 very clearly says "Compatible with PHP 7.1".
The good news might be that, for me, the code itself seems to work with PHP 7.1. So, a simple temporary workaround is to modify the file owncloud/apps/twofactor_totp/appinfo/info.xml, replacing the line
<php min-version="5.4" max-version="7.0" />
<php min-version="5.4" max-version="7.1" />
Of course this results in code signing warning messages.