  The JLMS formula relates the bulk and boundary relative entropies and is
fundamental to the holographic dictionary, providing justification for
entanglement wedge reconstruction. We revisit the replica trick for relative
entropy and find corrections of the JLMS formula in a variety of scenarios,
even after accounting for effects of quantum extremality. We analyze the
problem in the PSSY model, a model of Jackiw-Teitelboim gravity coupled to
end-of-the-world branes. We find non-perturbative (in $G$) corrections that are
always present, arising from subdominant replica wormhole gravitational saddles
that indicate the approximate error-correcting nature of AdS/CFT. Near
entanglement phase transitions, these saddles can get enhanced to large
corrections. We find $O\left(G^{-1/2}\right)$ corrections arising from area
fluctuations and $O\left(G^{-1}\right)$ corrections from incompressible bulk
quantum states. Lastly, we find our most surprising result, an infinite
violation of the JLMS formula after the Page time arising from a rank
deficiency in the bulk entanglement spectrum. We discuss similar calculations
in tensor networks and comment on the implications for bulk reconstruction.
