It seems you have a plug-in or theme activated which is trying to hook a function onto the admin_init hook, but the the function name they’ve given is not valid. Usually because the function doesn’t exist, and potentially because they’ve put a space in the callback name.
Try deactivating your plug-ins/ themes one by one to identify which one it is. Then you’ll just have to find the offending hooked function and work out why the name they’ve hooked onto admin_init invalid.