ubuntu 16.04 - wkhtmltopdf error - QSslSocket: cannot resolve CRYPTO_num_locks

wkhtmltopdf error on ubuntu 16.04 :
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QSslSocket: cannot resolve CRYPTO_num_locks                  ] 10%
QSslSocket: cannot resolve CRYPTO_set_id_callback
QSslSocket: cannot resolve CRYPTO_set_locking_callback
QSslSocket: cannot resolve sk_free
QSslSocket: cannot resolve sk_num

Solution :

sudo apt-get install libssl-dev=1.0.2g-1ubuntu4.10 openssl=1.0.2g-1ubuntu4