diff -up dovecot-2.2.36/src/auth/userdb-passwd.c.getpwentreset dovecot-2.2.36/src/auth/userdb-passwd.c

--- dovecot-2.2.36/src/auth/userdb-passwd.c.getpwentreset	2019-08-20 16:56:19.706885908 +0200

+++ dovecot-2.2.36/src/auth/userdb-passwd.c	2019-08-20 16:56:25.422867784 +0200

@@ -173,6 +173,9 @@ static void passwd_iterate_next(struct u

 			_ctx->callback(pw->pw_name, _ctx->context);

 			return;

 		}

+                /* getpwent might set errno to something even if it

+		   returns non-NULL. */

+		errno = 0;

 	}

 	if (errno != 0) {

 		i_error("getpwent() failed: %m");