The timatic entries can be viewed here:
https://www.iatatravelcentre.com/IN-...quirements.htm
U visas are no longer issued to those who have been granted Overseas Citizenship of India (OCI) status. Passengers with OCI status must travel with their OCI cards and will not be required to show a "U" visa. Passengers arriving at Delhi (DEL) and traveling without an OCI card are allowed to enter if they have a "U" visa on their old or current passport.
Furthermore, Persons of Indian Origin (PIO) Cards are no longer being issued. Passengers with PIO status must convert their PIO status to OCI status before the 31 March 2020. From the 31 March 2020, passengers with a PIO card will no longer be allowed to enter.
Passengers with a Registration Certificate/Residential Permit must also travel with the supporting documents allowing them to stay in India, e.g. PIO.
Expired passports are mentioned a few times:
Valid visa stickers in expired passports are acceptable if accompanied by a valid passport of the same nationality of the expired passport. Passengers must have both the expired and the valid passport.
Valid ETA issued on expired passports are accepted if accompanied by a valid passport of the same nationality. Passengers must have both the expired and the valid passport.
The OCI and new passport <20 >50 is now a special warning:
Warning:
Passengers younger than 20 years must apply for a new OCI card every time they get a new passport.
Passengers older than 21 and younger than 49 years are not required to apply for a new OCI card when they get a new passport. They can present the OCI card with a valid passport.
Passengers older than 50 years must apply for a new OCI on the first renewal of the passport after 50 years. If the OCI card is issued for the first time after the passenger is older than 50 years, there is no need to issue a new OCI ever time a new passport is issued.