  A recent paper by Ag\'elas [Generalized Riemann Hypothesis, 2019,
hal-00747680v3] claims to prove the Generalized Riemann Hypothesis (GRH) and,
as a special case, the Riemann Hypothesis (RH). We show that the proof given by
Ag\'elas contains an error. In particular, Lemma 2.3 of Ag\'elas is false. This
Lemma 2.3 is a generalisation of Theorem 1 of Vassilev-Missana [A note on prime
zeta function and Riemann zeta function, Notes on Number Theory and Discrete
Mathematics, 22, 4 (2016), 12-15]. We show by several independent methods that
Theorem 1 of Vassilev-Missana is false. We also show that Theorem 2 of
Vassilev-Missana is false.
  This note has two aims. The first aim is to alert other researchers to these
errors so they do not rely on faulty results in their own work. The second aim
is pedagogical - we hope to show how these errors could have been detected
earlier, which may suggest how similar errors can be avoided, or at least
detected at an early stage.
