404 after Update

Hello,
after update to the latest version and the latest "admin" version, i have a 404 error if i will login (/admin).
What can i do?
Greetings Alex

The grav.log said:
[2017-01-20 10:10:29] grav.WARNING: Plugin 'admin' enabled but not found! Try clearing cache with bin/grav clear-cache [] []

Did clearing the cache help?

guess admin folder is empty now...
look here:
https://github.com/getgrav/grav-plugin-admin/issues/939#issuecomment-273940443
or in my post below: no access to admin...

I have Webspace (no Server no Shell access)

Backup your site.

Download v. 1.2.9 from GitHub as ZIP file

Unzip it.

Name the folder 'admin'.

Transfer the folder named 'admin' to your site (/user/plugins/).

Looks like a problem in installing Admin has caused it to not being updated. Instead, the folder is now empty. Reinstall Admin as @core said, we're looking into that.

Fixed on GPM side, more info: https://github.com/getgrav/grav/issues/1267#issuecomment-274295364

Try uncommenting RewriteBase in your htaccess. This worked for me: https://learn.getgrav.org/troubleshooting/page-not-found