You upgraded to the snapshot version of 2.5 NOT the stable release of 2.4. You may want to use the stable version (2.4) or at the very least the milestone version 2.5M1. Unless you have a lot of knowledge, snapshot versions can be very frustrating as they tend to be more buggy.
You do not give enough information to help.
If your items are linked to MQTT binding, then this is known issue (just search the forum), otherwise, please give more info.
