I have an EU Blue Card and have recently received a new passport. According to the website of the Immigration office in Berlin (https://service.berlin.de/dienstleistung/326798/en/), in this case, (only) the plastic card of my Blue Card residence permit is no longer valid, since this plastic card refers my old passport, and my residence title EU Blue Card is still valid.
They also say I can easily re-enter Germany with an expired blue card, old passport, and new passport. I’m planning to travel to Portugal next month, and I’m worried I’ll have issues entering Portugal with an expired blue card :’) Has this happened to anyone before? Thanks and sorry for the long post