I get the same thing. I’ve tried all of the steps on https://us.battle.net/support/en/article/13934 but no luck. Only started happening since the pre-patch went live.
Full Error:
"The CAS system was unable to initialize: Unable to initialize CAS from build info file. Code version does not match .build.info.
Unable to initialize CAS from patch service: provided version info string(s). VersionInfo:eu. CDNinfo: eu
Hoping this can be fixed without a re-install. Not even sure if that will work?