: Occasionally, antivirus software can interfere with game files, causing verification issues. Temporarily disabling it might help.
When the launcher displays "Preparing Game Data" or "Verifying," the client is not simply idling. It is conducting a checksum comparison of your local game files against the server’s master records. This ensures that critical assets—such as map data, unit models, and patch binaries—are not corrupted or modified. starcraft 2 preparing game data verified