Lunar eclipses on Easter day

[ricci]

Easter falls on the Sunday which follows the first Full Moon after the spring equinox. And lunar eclipses occur only at Full Moon!
At first view this phenomena seems impossible, but we know that for the ecclesiastical rules the spring equinox is fixed at March 21 and
that the Full Moon is taken from ecclesiastical tables. Sometimes the astronomical ephemerides differ from the ecclesiastical tables.

www.pierpaoloricci.it/dati/eclissipasqua_eng.htm

[circumpolar (Matt)]

This is a good page about Easter calcs and common Myths found on the internet.

http://www.gmarts.org/index.php?go=412

Easter is based upon Paschal Full Moon (PFM) dates and NOT Astronomical Full Moons dates, and each (PFM) is the particular Ecclesiastical Full Moon (EFM) date after March 20,
Provided it does not coincide with Passover.

Yes, it is complicated!

At the bottom of this linked webpage is a list of differing calculation methods.