The orbital pericenter precession in the 2PN approximation

Recent article Revisiting the 2PN Pericenter Precession in View of Possible Future Measurements published by Iorio (Universe 6(4):53, 2020. https://doi.org/10.3390/universe6040053 ) argues that calculations of the secular 2PN precession of the orbital pericenter of a binary system accomplished by Damour and Schäfer (Nuovo Cim B Ser 101B(2):127–176, 1988. https://doi.org/10.1007/BF02828697 ) and Kopeikin and Potapov (Astron Rep 38(1):104–114, 1994) with different mathematical techniques are inconsistent, differ from each other and do not agree with the result obtained by L. Iorio. The purpose of this communication is to demonstrate that the article by Iorio (2020) is erroneous, suffers from misconceptions and cannot be trusted.