Hydrolyzes RNA 2',3'-cyclic phosphodiester to an RNA 2'-phosphomonoester (PubMed:25239919). In vitro, can also ligate 5' and 3' half-tRNA molecules with 2',3'-cyclic phosphate and 5'-hydroxyl termini, respectively, to the product containing the 2'-5' phosphodiester linkage. This reaction does not require ATP and is reversible (PubMed:6347395 and PubMed:8940112). a 3'-end 2',3'-cyclophospho-ribonucleotide-RNA + H2O = a 3'-end 2'-phospho-ribonucleotide-RNA + H(+) Monomer. Disruption abolishes ligase activity in cell lysates, but mutants grow normally under laboratory conditions. Belongs to the 2H phosphoesterase superfamily. ThpR family. Was originally thought to be a 2',5'-RNA ligase.