I am looking for a way to prevent users from logging in in a certain time span, let's say for a few days after new year's eve to check all data in the system.

I thought about the "Login Hours" on a profile level, but it would be nice if there was a faster (more global) way to do this.

Also it would be really great if the user gets a notification on login, why he can't access the system right now, that I define (e.g., "you can't login because we are checking data...").

Do you have any ideas or experience with that?

Attribution to: Nisse Knudsen

Possible Suggestion/Solution #1

I recommend a "maintenance" profile. We have one with all of the login hours set to midnight, preventing users from logging on completely. Another option would be to have your profile set to only show a web tab with your maintenance message.

The nice thing about maintenance profiles is that you can mass update all of your users via the Data Loader (just make sure you don't lock out your system admins.)

Edit

Note, this cannot be accomplished with Permission Sets since they only add to a user's access.

Attribution to: Mike Chale
This content is remixed from stackoverflow or stackexchange. Please visit https://salesforce.stackexchange.com/questions/4773