Hi, I finally managed to get Calendar Server (version 4.2) to run on my Mac (10.7.5). It runs without problems if I use a self-signed certificate. However, I wanted to go a step further, and introduce my root and intermediate certificates in the process. However, the server fails with the output listed at the end of this message. This is the relevant part of caldavd.plist: <!-- SSL/TLS --> <!-- Public key --> <key>SSLCertificate</key> <string>/usr/local/caldavd/etc/caldav-server.crt</string> <!-- SSL authority chain (for intermediate certs) --> <key>SSLAuthorityChain</key> <string>/usr/local/caldavd/etc/chain.crt</string> <!-- Private key --> <key>SSLPrivateKey</key> <string>/usr/local/caldavd/etc/caldav-server.key</string> I created these, using roughly these steps: openssl genrsa -des3 -passout pass:stdin -out root-ca.key 4096 openssl req -new -key root-ca.key -out root-ca.csr openssl x509 -req -days 4384 -in root-ca.csr -signkey root-ca.key \ -extfile GenerateCertificate.cfg -extensions v3_ca -out root-ca.crt openssl pkcs12 -export -in root-ca.crt -inkey root-ca.key -out root-ca.p12 openssl pkcs12 -in root-ca.p12 -out root-ca.pem -nodes intermediate: openssl genrsa -des3 -out intermediate-ca.key 2048 openssl req -new -key intermediate-ca.key -out intermediate-ca.csr openssl x509 -req -days 4384 -in intermediate-ca.csr \ -CA root-ca.crt -CAkey root-ca.key \ -set_serial 1 -extfile GenerateCertificate.cfg -extensions v3_ca -out intermediate-ca.crt openssl pkcs12 -export -in intermediate-ca.crt -inkey intermediate-ca.key \ -chain -CAfile root-ca.crt -out intermediate-ca.p12 openssl pkcs12 -in intermediate-ca.p12 -out intermediate-ca.pem -nodes leaf certificates: export name=caldav-server openssl genrsa -des3 -out $name.key 2048 openssl req -new -key $name.key -out $name.csr openssl x509 -req -days 1095 -in $name.csr -CA root/intermediate-ca.crt -CAkey root/intermediate-ca.key \ -set_serial 1 -out $name.crt openssl pkcs12 -export -in $name.crt -inkey $name.key -chain -CAfile root/intermediate-ca.pem -out $name.p12 openssl pkcs12 -in $name.p12 -out $name.pem -nodes And then produces chain.crt by doing: cat caldav-server.crt intermediate-ca.crt root-ca.crt > chain.crt I created a virtualenv for caldav server, where I'm running Twisted 12.3.0 (same problem appears with 12.0.0). Any pointer toward resolving this issue would be most helpful :) Thanks, Nikola This is the output I'm getting: 2013-03-31 20:02:24+0200 [-] [caldav-0] [-] Unhandled Error 2013-03-31 20:02:24+0200 [-] [caldav-0] Traceback (most recent call last): 2013-03-31 20:02:24+0200 [-] [caldav-0] File "/usr/local/caldavd/lib/python2.7/site-packages/Twisted-12.3.0-py2.7-macosx-10.7-intel.egg/twisted/python/log.py", line 73, in callWithContext 2013-03-31 20:02:24+0200 [-] [caldav-0] return context.call({ILogContext: newCtx}, func, *args, **kw) 2013-03-31 20:02:24+0200 [-] [caldav-0] File "/usr/local/caldavd/lib/python2.7/site-packages/Twisted-12.3.0-py2.7-macosx-10.7-intel.egg/twisted/python/context.py", line 118, in callWithContext 2013-03-31 20:02:24+0200 [-] [caldav-0] return self.currentContext().callWithContext(ctx, func, *args, **kw) 2013-03-31 20:02:24+0200 [-] [caldav-0] File "/usr/local/caldavd/lib/python2.7/site-packages/Twisted-12.3.0-py2.7-macosx-10.7-intel.egg/twisted/python/context.py", line 81, in callWithContext 2013-03-31 20:02:24+0200 [-] [caldav-0] return func(*args,**kw) 2013-03-31 20:02:24+0200 [-] [caldav-0] File "/usr/local/caldavd/lib/python2.7/site-packages/Twisted-12.3.0-py2.7-macosx-10.7-intel.egg/twisted/internet/selectreactor.py", line 151, in _doReadOrWrite 2013-03-31 20:02:24+0200 [-] [caldav-0] why = getattr(selectable, method)() 2013-03-31 20:02:24+0200 [-] [caldav-0] --- <exception caught here> --- 2013-03-31 20:02:24+0200 [-] [caldav-0] File "/usr/local/caldavd/lib/python2.7/site-packages/twext/internet/sendfdport.py", line 295, in doRead 2013-03-31 20:02:24+0200 [-] [caldav-0] description, protocol) 2013-03-31 20:02:24+0200 [-] [caldav-0] File "/usr/local/caldavd/lib/python2.7/site-packages/twext/web2/metafd.py", line 103, in createTransport 2013-03-31 20:02:24+0200 [-] [caldav-0] transport.startTLS(self.contextFactory) 2013-03-31 20:02:24+0200 [-] [caldav-0] File "/usr/local/caldavd/lib/python2.7/site-packages/Twisted-12.3.0-py2.7-macosx-10.7-intel.egg/twisted/internet/_newtls.py", line 179, in startTLS 2013-03-31 20:02:24+0200 [-] [caldav-0] startTLS(self, ctx, normal, FileDescriptor) 2013-03-31 20:02:24+0200 [-] [caldav-0] File "/usr/local/caldavd/lib/python2.7/site-packages/Twisted-12.3.0-py2.7-macosx-10.7-intel.egg/twisted/internet/_newtls.py", line 139, in startTLS 2013-03-31 20:02:24+0200 [-] [caldav-0] tlsFactory = TLSMemoryBIOFactory(contextFactory, client, None) 2013-03-31 20:02:24+0200 [-] [caldav-0] File "/usr/local/caldavd/lib/python2.7/site-packages/Twisted-12.3.0-py2.7-macosx-10.7-intel.egg/twisted/protocols/tls.py", line 602, in __init__ 2013-03-31 20:02:24+0200 [-] [caldav-0] contextFactory.getContext() 2013-03-31 20:02:24+0200 [-] [caldav-0] exceptions.AttributeError: 'NoneType' object has no attribute 'getContext'