The bug
/execute
store ignores value validation, allowing you to set values which would be considered invalid when used in the respective command.
Partially relevant /r/Mojira discussion
Affected situations
bossbar max
bossbar value
read-only scoreboard objectives
How to reproduce
bossbar max
Create a bossbar
/bossbar add custom:test "test"
Try setting a negative maximum
/bossbar set custom:test max -1
→ ✔ It fails as expected
Create a scoreboard objective and set a negative score
/scoreboard objectives add test dummy /scoreboard players set value test -1
Try storing the score as
bossbar max
/execute store result bossbar custom:test max run scoreboard players get value test
Get the
bossbar max
/bossbar get custom:test max
→ ❌ It shows -1
Read only scoreboard objectives
Create a read only scoreboard objective and have it displayed on the sidebar
/scoreboard objectives add health health /scoreboard objectives setdisplay sidebar health
Take damage or heal to update the score (see MC-111729)
Try setting a value for the
health
objective/scoreboard players set @s health -1
→ ✔ It fails as expected
Create a scoreboard objective and set a negative score
/scoreboard objectives add test dummy /scoreboard players set value test -1
Try storing the score as value for the read-only objective
/execute store result score @s health run scoreboard players get value test
→ ❌ Your
health
score changed to -1
Related issues
Comments


New fact, it's only a visual bug, when you test with the "get" command, these are the expected values.
And when you quit the world et reopen it, the problem is solved.

Confirm for 1.13-pre1
I found the best way to fix it, just set the visibility to false, and after reset to true, it works but not as expected by the game ...

Confirm for 1.13-pre2

Confirmed for 1.13.1.
Can confirm in 21w03a.
Can confirm in 21w06a.
Confirm for 18w22c
I tried to do some tests directly with NBT tags with the following commands in
minecraft:repeating_command_block
:When you create bossbar before executing previous commands and after you execute commands, no problems, it works.
But when the targeted entity dies, it broken.
After that, I tried another test with only "set value" of bossbar and no problems even if the targeted entity die and after yo summon another entity.
I think the problem is when you set the max value in the same time you set the value of the bossbar.
the only way I found to solve this problem is to remove the bossbar and recreate it.