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Err30 is a shutter malfunction. Err50 is a more general failure message about electronics in the camera. (Or sometimes, if an incompatible non-Canon lens assembly is on the camera body, it may produce this sort of error.)
If there's any chance your lens mount is dirtied in the slightest, then take a clean, dry, soft cloth, and gently wipe the contacts on both the lens mount and the lens assembly - with the camera Off and the lens dismounted of course - and see if that cures the problem.
How old is the camera? in months or years since you bought it.
Has the camera been dropped onto a hard or not-soft surface, or otherwise subjected to mechanical shock(s) in its lifetime?
Has the camera been operated in or subjected to, temperatures below 32 degrees F (freezing point) or above about 100 degrees F ?
Has it ever been subjected to a humidity higher than 85 % or gotten wet ?
Has the camera been operated in a gritty or sandy environment, such as a beach, a seaside, a construction site, or the like?