Error on every page 3.7.1 update

Thank you, @mikeverduin. The workaround worked for me too.

I am hoping that the maker of BackWPup will have a more permanent solution in their next update.

Thank you!

@mikeverduin
thank you all for the report and the solution, and yes, we already aware of the issue and it will be fixed in the next update.
Thank you again!

I’ll mark it as resolved again. Thanks.

I experience the same message on every page of my website when logged in as admin.
QUOTE:
“Deprecated: Non-static method BackWPup_Admin::admin_css() should not be called statically in C:\xampp\htdocs\mywebsite.com\wp-includes\class-wp-hook.php on line 287”
UNQUOTE.
Please advise.

we already aware of the issue and the fix will be included in the next update, for now, you can just ignore the warning, or replace backwpup/inc/class-admin.php with this one:
https://gist.github.com/cuongdcdev/267bff4e4a68b6d8409e18ab8a5b0ee7

I hope that helps!
@jbrandenburg