Manual Update 500 error Downloaded latest release, pushed app-new to server, renamed app to app-old, renamed app-new to app.

Try to go to admin, and I get a 500 error.

Server error log shows.
2017-11-15 12:29:29 Error   500 GET /admin HTTP/1.1

Any ideas.
Trying to update an install that hasn't been updated in a long time.
Going from 2.6.2911 to 2.6.2974

I can still get to admin if I use the old app by renaming app to app-new, and app-old to app
Re-downloaded manual update, and pushed to the server via ftp again fixed the issue. Download might have been corrupt is my only thought.