curl command - Unable to load client cert -8018

I'm trying to connect to a secure webservice throught a proxy using the curl command, but I get the follow error:

Unable to load client cert -8018.

Complete log:

[e-ballo@myserver]#   curl  -v -x proxy01.net:8080 https://endPointURL.com/SOAP --key ./cert.crt --cert ./cert.crt -capath=/etc/pki/tls/certs
* About to connect() to proxy proxy01.net port 8080 (#0)
*   Trying 10.0.3.64... connected
* Connected to proxy01.net (10.0.3.64) port 8080 (#0)
* Establish HTTP proxy tunnel to endPointURL.com:443
> CONNECT endPointURL.com:443 HTTP/1.1
> Host: endPointURL.com:443
> User-Agent: curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.14.3.0 zlib/1.2.3 libidn/1.18 libssh2/1.4.2
> Proxy-Connection: Keep-Alive
>
< HTTP/1.0 200 Connection established
<
* Proxy replied OK to CONNECT request
* Initializing NSS with certpath: sql:/home/e-ballo/
* Unable to initialize NSS database
* Initializing NSS with certpath: none
*   CAfile: /etc/pki/tls/certs/ca-bundle.crt
  CApath: none
* Unable to load client cert -8018.
* NSS error -8018
* Closing connection #0
curl: (58) Unable to load client cert -8018.

Any idea what this error means ? and how can I fix it ?

Thanks in advance,

Solution

I already fixed this problem, so I will post the solution. Maybe can help to somebody.

My version of curl was compiled with the Netscape Security System (NSS) libraries instead of the openSSL libraries. Versions of curl compiled with these two libraries use different certificate access methods. I was calling a flat file, which is the openSSL method. Another solution will be get NSS installed, (already there on most Red Hat derivatives) and create a cert9.db file, import your certificate and key (after converting to a P12 with openssl -don't forget to add a "freindlyName" or nickname) into that db using pk12util. Then you call the cert by it's nickname and give the password for the db.

The other option is get or compile a version of curl using the openssl libraries. RedHat 5, ubuntu or windows versions of curl are frequently already compiled that way. Red Hat 6 comes with curl compiled for NSS.