YuraLons are you experiencing the error when you open the install page, or during the installation itself ?
yingliangzhang same question to you, at what point of the installation do you get the error ?
Right now I can't see what could be wrong.
When the site is not installed, it looks like we don't define a view
configuration for Laravel https://github.com/flarum/core/blob/v0.1.0-beta.11.1/src/Foundation/UninstalledSite.php#L106
But as soon as the site gets in the "installed" mode, the view
key of the config is defined here https://github.com/flarum/core/blob/v0.1.0-beta.11.1/src/Foundation/InstalledSite.php#L161
The fact we don't define a view
could be the issue, but then I don't understand why the problem would surface now. PHP behavior for unknown keys has not changed, we have not changed the config in any recent version https://github.com/flarum/core/blame/d492579638fb52dafbfe65f1f36a95eb6047f7f3/src/Foundation/UninstalledSite.php#L106 and there was no recent changes to the ServiceProvider
of Laravel either https://github.com/laravel/framework/commits/5.7/src/Illuminate/Support/ServiceProvider.php
It seems it's an isolated case for now, otherwise we would have gotten way more reports if everyone started experiencing it. I'm not able to try an installation myself right now.
Can you give us more insights on the hosting you are using (Company, PHP version, web server ...). Also does it systematically fails on all attempts or did you maybe successfully get Flarum installed elsewhere recently ?