One player has a modified map file (even accidentally, due to disk corruption). The checksum fails, and the match aborts. This is why ladder forces a map re-download if verification fails.
For further troubleshooting, check the Official Blizzard SC2 Forums or verified community threads on Reddit .
This issue typically stems from a mismatch between the Battle.net app settings and the local game client, or interference from background system services.
Until then, the next time you see that progress bar and the words “Preparing game data,” know that your computer is orchestrating a silent symphony: decompressing archives, building collision grids, syncing clocks, and warming up textures — all to deliver the crisp, responsive, beautifully balanced chaos that is StarCraft II .
Open Battle.net; it will show "Install." Click below it.
