GUID URL Question

Background: The guid should be just what the name says: a globally unique identifier. A unique string or number, not related to a public address at all. However, some functions, namely for images, are still using it for URLs. There are plans to fix that somewhere in the future, see #6492.

For now, you can safely change the value of that field, as long as you keep the correct post ID. Search in other fields to to catch all references.