It is known that in order to enter the Schengen area a non-EU citizen should have a passport which
However I was not able to find any information on what happens if a third-country national is a EU long-term resident in a Schengen member country, has a passport issued some 9,5 years ago and he/she extends the validity of passport in the consulate of his/her country of citizenship for, say, another 10 years while staying in the Schengen area.
The question is: will this extended passport be valid for traveling within the Schengen area (at least until 10 years from the date of issue of the passport, i.e. for a few months remaining until the passport becomes exactly 10 years old)?
I am not sure to which extent the answer to this question depends on a specific Schengen country to which one wants to travel. If this is the case, I am particularly interested in the possibility of traveling to Austria, Germany, Poland and Italy.