A blocking error occurs when a player goes up at the net to block the ball coming over, but fails to do so legally. Blocking errors are not officially recorded for poor form in blocking, such as failing to close the block or having improper timing. Instead, most official blocking errors are called for illegal movements at the net.
Unofficially, the most common blocking error is failing to form the block properly.
Tooling occurs when a hitter hits the ball off of the hands of the blocker, causing the ball to then land out of bounds. When a tool happens, the hitting team wins the point, as the blocking team was the last to touch the ball before it went over the net. Often, if a block is too strong, hitters will intentionally hit off the side of the block in order to cause a tool. If blockers allow the hitter to tool off of their hands, this can be considered a blocking error, even if it is not recorded on game statistics.
Official blocking errors occur when a blocker commits a net or centerline violation. If the player touches the net when they are in the process of blocking, they will be called for a net violation and their team will lose the point. Similarly, if their foot crosses the centerline in the process of jumping or landing, they will be called for a centerline violation and lose the point. These two mistakes most often happen when a player has the improper form in the approach to their block. If they are jumping horizontally instead of vertically, they can travel too close to the net and accidentally bump into it or step over the centerline.
Blockers can also be called for a back row blocking violation. If the player is in the back row of the rotation for that point, they are not allowed to block at the net. This is similar to back row players not being able to jump and hit the ball from in front of the ten-foot line. This mistake most often happens when a setter is in the back row and attempts to block at the front of the court.
The last fault a blocker can make is if they reach over the net. They must keep their hands on their side of the net until the ball is moving toward their side of the court. If they touch the ball while it is still moving on the opposite side of the net without any movement toward their side, they will be called for reaching. This most often happens when there is a pass close to the net, and the second player to touch the ball is still attempting to come into contact. In this case, the blocker is not allowed to touch the ball until after the ball is moving toward their side of the court.
In the game statistics, blocking errors are only called for the net and centerline violations, reaching over the net, or back row blocking. Blocking errors are not marked unless the referee calls the violation. If they miss the violation and the play continues, no error is recorded. In these cases, the player who commits the error receives the mark on the statistics sheet. If the blocking error occurs while a hitter from the other team is sending the ball over the net, the hitting player receives a kill on the statistics sheet.