Bug Block

Bug Blocks (バグブロック, Bagu Burokku) are computer bugs in the shape of a cube that appear as a critical part of the gameplay in Kingdom Hearts coded.

Kingdom Hearts coded
Bug Blocks appear in all of the data worlds from Jiminy's Journal; they are a product of the data "bugs" from digitizing the journal. The Data Sora must destroy Bug Blocks in order to progress through worlds and the storyline, as well as fix the data worlds.

Bug Blocks are mirrored from the "fire walls" and bugs in real computers. So, when Mickey digitized the journal, they are the bug's. Sora must defeat them to stop the "virus" of the journal.

In Episode 8, it was revealed that Naminé's manipulation of Sora's memories in Kingdom Hearts: Chain of Memories was the primary cause of the appearance of the Bug Blocks. The data Naminé confirmed this to King Mickey and the Data Sora, along with informing them of the suffering of some connected to Sora's heart, namely Terra, Aqua, Ventus, Roxas, the real Naminé, Axel, and Xion.

Appearance
There are different types of blocks: red ones are normal, those marked with a star contain a prize, and grey blocks cannot be destroyed.