OpenVPN.ovpn combined all certification and private key.

edit your client.ovpn:

#vim client.ovpn

Delete these line or comment it.
ca ca.crt
cert client.crt
key client.key
tls-auth ta.key 1

Add these content to client.ovpn

<ca>
—–BEGIN CERTIFICATE—–
ca.crt contend
—–END CERTIFICATE—–
</ca>

<cert>
—–BEGIN CERTIFICATE—–
client.crt contend
—–END CERTIFICATE—–
</cert>

<key>
—–BEGIN PRIVATE KEY—–
client.key contend
—–END PRIVATE KEY—–
</key>
key-direction 1 #must have this line

<tls-auth>
—–BEGIN OpenVPN Static key V1—–
ta.key contend
—–END OpenVPN Static key V1—–
</tls-auth>