Because in 1.19.50, the new execute syntax became mandatory, so you’ll need to switch to that. See also this information on bedrock.dev.
In 1.20.5 a new system for storing item data has been introduced to Java Edition in Snapshot 24w09a. Anything relating to items (such as /give, /item or loot tables) have a different format now. The gist of it is this: Unstructured NBT data attached to stacks of items (tag field) has been replaced with structured ‘components’ that go in [] and are comma separated. For example: /give @p diamond_pickaxe[damage=10,custom_model_data=7] For a list of how item components are structured, see this article on the minecraft.wiki.
Detect a specific item (in the Inventory, in the selected slot, on the ground)?
Give an item a custom tag to identify it by?
Select players with exactly X of a certain item?
Detect rightclick or leftclick (on an item)?
Give a special item (Bedrock)?
Change an item while it’s in the players inventory?
Do custom crafting?
Make a shop? / Buy items?
Generate a random number?
Store an NBT value to a score, and vice versa? (1.13+ only)
Check if a score is equal to, greater than, or less than another score?
Find an entity that has the same score as another entity?
Summon/Teleport an entity/player at/to a position defined in a score?
Detect a change in score?
Link an entity to another entity through scoreboards?
Find the player / entity with the highest / lowest score?
Activate a command once when a player does something (e.g: enters an area)?
Do something on all players in certain area(s)?
Target a player above/below a certain Y level?
Detect when a player died?
Detect when a player kills an entity/other player?
Detect a player joining (for the first time)?
Store a players inventory (and give it back later)?
Detect a player looking at something (entity / position)
Do something if a command block wasn’t successful?
Do something (e.g: kill) to the entity I just found with /execute if entity (testfor)?
Add a delay to a command block?
Check if there are exactly X players matching a selector?
Do conditions with functions?
Point a compass towards a player?
Summon an entity/projectile flying in the direction the player is looking?
Make a scoreboard ID system?
Make one mob attack another mob/player?
Do raycasting?
Make a circle (of blocks / entities)?
Detect when a mob has died
Make hostile mobs friendly / dissable PvP
Setup, configure and add multiple dialogues to NPCs?
a fake player?
a range? / those two dots ..?
command context?
Select an entity with multiple scoreboard tags?
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