I need to connect to an external server via SSL which only accepts certificates exchange following this architecture :

Client (my Nodejs server) -----http-----> (Reverse?) Proxy ----https-----> External Server asking for certificate.

I don't own the external server, but they have my certificates installed in their system.

I used Let's Encrypt to generate certificates, so I have 4 files :

```
privkey.pem --> Private Key
cert.pem --> Public Key
chain.pem --> Certificate Chain
fullchain.pem --> Concatenation of cert.pem and chain.pem

```

Current, not working, apache 2.4.33 vhost configuration :

```
<VirtualHost *:80>
    SSLProxyEngine On
    SSLProxyVerify require

    SSLCertificateFile path/fullchain.pem
    SSLCertificateKeyFile path/privkey.pem

    SSLProxyMachineCertificateChainFile path/fullchain.pem
    SSLProxyCACertificateFile path/fullchain.pem
    # mydomain.certandkey.pem is a concatenation of cert.pem and privkey.pem
    SSLProxyMachineCertificateFile mydomain.certandkey.pem

    ProxyRequests Off
    RewriteEngine On
    #ProxyPreserveHost On
    #<Proxy *>
    #Order deny,allow
    #Allow from all
    #</Proxy>

    ProxyPass / https://external.server.com/
    ProxyPassReverse / https://external.server.com/
</VirtualHost>

```

The apache error log is 

```
AH02252: incomplete client cert configured for SSL proxy (missing or encrypted private key?)
[date] [ssl:emerg] [pid 76986] AH02312: Fatal error initialising mod_ssl, exiting.
AH00016: Configuration Failed

```

It seems to come from `SSLProxyMachineCertificateFile` as it goes away when I comment the corresponding line (but connection doesn't doesn't work).

Does any one have an idea how to fix this or meet a similar connection situation ?

I've spent my last two days looking over the internet and trying many configurations, it drives me crazy.

Thank you very much.