If your passport has expired when applying for a Vietnam visa, you can only obtain a visa once you renew your passport. Vietnam requires that all foreign visitors have a valid passport that is at least six months from the date of entry.
To obtain a Vietnam visa, you will need to provide a valid passport that meets the requirements. If your passport has expired, you will need to renew it before applying for a visa. Once you have a valid passport, you can apply for a Vietnam visa through the appropriate channels, such as the Vietnamese embassy or consulate in your home country, or through an online visa service.
It is important to check the specific requirements for obtaining a Vietnam visa based on your citizenship and travel plans, as the process and requirements can vary. In addition to a valid passport, you may also need to provide other documentation, such as a visa application form, a passport photo, and proof of travel arrangements.
If you have any questions or concerns about obtaining a Vietnam visa with an expired passport, it is recommended that you contact the appropriate authorities or a reputable visa service for guidance.