QSslSocket: cannot resolve SSLeay
QSslSocket: cannot call unresolved function CRYPTO_num_locks
QSslSocket: cannot call unresolved function CRYPTO_set_id_callback
QSslSocket: cannot call unresolved function CRYPTO_set_locking_callback
QSslSocket: cannot call unresolved function SSL_library_init
QSslSocket: cannot call unresolved function SSLv23_client_method
QSslSocket: cannot call unresolved function sk_num
QSslSocket: cannot call unresolved function SSLv23_client_method
QSslSocket: cannot call unresolved function SSL_library_init
Error: Failed loading page https://api.pagar.me/1/boletos/live_ckbcm9fpmatezc83f28hw555e (sometimes it will work just to ignore this error with --load-error-handling ignore)
Exit with code 1 due to network error: UnknownNetworkError
QSslSocket: cannot call unresolved function CRYPTO_num_locks
QSslSocket: cannot call unresolved function CRYPTO_set_id_callback
QSslSocket: cannot call unresolved function CRYPTO_set_locking_callback
Solução foi atualizar versão do wkhtmltopdf para versão 0.12.5, como instruído nesse link: