Blizzard
Updated: 19 hours ago Article ID: 10994
You will receive this error when you reach the limit of unique instance IDs allowed per hour or day. Each time you enter a new dungeon or raid (or the same dungeon or raid after resetting it) you are given a new instance ID.
Below are the limits. Customer Support cannot assist with bypassing the limits.
Modern WoW
You can enter up to ten individual instanced zones per hour. The limit is per account, and cannot be avoided by changing characters. You can still queue for random instances in the Dungeon Finder while under effect of this limit, but you will not be given a Deserter debuff if you cannot enter the dungeon.
WoW Classic and Burning Crusade Classic
In WoW Classic you can enter up to five individual instanced zones per hour, and a maximum of 30 instanced zones per day. The limit is per character. 40-player raid instances are not affected by the 30-per-day limit on entering dungeons.