我对laravel framework Lumen(5.8.12)也有同样的问题，我通过返回5.8.4版解决了这个问题.
The Origin of the problem seems to be the Symfony VarDumper Component (\vendor\symfony\var-dumper\Cloner\Data.php, line 302):
$dumper->dumpScalar($cursor, 'default', '^');
Should be:
$dumper->dumpScalar($cursor, 'default', '');
It is there for a useful reason. In terminal if you hover over the mouse on that ^ sign it will show you the file path from where this dump is coming from! I think it's really a useful thing but I don't see it working in browser. So, it should either be removed from borwser or fix the issue there.