Could someone help me how to create a validation rule that will fulfill the following requirement: When Quote name contains prefix "H", the opportunity owner should not be changeable. I tried with contains and is changed, but unfortunately it doesn't work.
I think you can't achieve this using the Validation rule. You have to use a trigger for this. While changing opportunity owner, you need to check if there is any quote which is associated with this opportunity which has "H" as a prefix. To get the related quotes of the opportunity, you can use trigger and add prevent owner change if there is any quote record is available where the prefix is "H".