Passport not valid for long enough
All foreign travelers entering Vietnam must hold a passport valid for at least six (6) months beyond their date of entry, with at least two (2) blank pages remaining for entry and exit stamps.
What the officer assesses: Whether your passport stays valid for at least six months after the day you arrive, and still has two empty pages.
Where this comes from 3 official sources
All foreign travelers entering Vietnam must hold a passport valid for at least six (6) months beyond their date of entry, with at least two (2) blank pages remaining for entry and exit stamps.
Vietnam visa requirements, Overview of Vietnam entry requirements
a) Passport valid for at least six months beyond the intended date of departure from Viet Nam.
Viet Nam's visa procedures, Regular visa: apply in person, required documents
Electronic visa or e-visa is issued to foreigners with valid passports.
Understanding Viet Nam's e-visa, General information
Evidence that addresses it
- The photo page of your passport, showing the date it runs out
- A new passport first, if yours runs out within six months of your trip