The user you are trying to block has already been blocked and hidden.
Since you do not have the hideuser right, you cannot see or edit the user's block.

If the user is already blocked, overwrite the existing block.

You do not have permission to edit the list.

You cannot reset user's passwords because you are blocked globally.

You do not have the necessary permission.

The article you tried to create has been created already.

You cannot reply because this topic has been hidden.

You currently are not able to participate, because you do not have the required rights.

You cannot block or unblock other users because you are yourself blocked.

The filter you requested is hidden, and you cannot view its history.

You are about to block yourself! Are you sure you want to do that?

The user page for the ip you

Used as (red) error message on [[Special:Block]] when you try to change (as sysop without the hideuser right) the block of a hidden user.

You are already uploading the file "$1".

The page has been deleted since you fetched its timestamp.

You don't have permission to block users.

The title you are currently trying to import to already exists on the source wiki.

This user has been blocked and hidden previously.
The suppress log is provided below for reference:

You made modifications to the checklist that are not yet saved. Are you sure you want to discard the changes?

The environment has been checked.
You cannot install MediaWiki.

The environment has been checked.
You cannot install MediaWiki.

[[Special:Contributions/$1|$1]] has been blocked.<br />
See the [[Special:BlockList|block list]] to review blocks.

You don't have permission to hide user names from the block log.

Changes to pages you have visited since the changes occurred.

You cannot unblock this user, as their username has been hidden.