Class 'IPS\Dispatcher' not found

[Abandoned Jerks]

Hey guys.   Trying to upgrade my development environment to make sure the upgrade goes smoothly on the production forums.  It's currently running 4.0.x (I think) and am trying to upgrade to 4.1.x. (SVN 22ff7)

I am getting the following error, even if I completely blow away my docs directory and unzip the IPS Community zipfile into it.  Permissions look fine.  Using PHP7 and nginx.  This was working with 4.0.

Stack trace:
#0 [internal function]: IPS\IPS::exceptionHandler(Object(Error))
#1 {main}
  thrown in /var/www/.../docs/init.php on line 501" while reading response header from upstream, client: ..., server: ..., request: "GET / HTTP/1.1", upstream: "fastcgi://unix:/var/run/php5-fpm.sock:", host: "..."
2017/06/10 18:21:01 [error] 4920#4920: *8 FastCGI sent in stderr: "PHP message: PHP Fatal error:  Uncaught Error: Class 'IPS\Dispatcher' not found in /var/www/.../docs/init.php:501