Thanks for your fast answer and your assistance.

I only changed the password for the keystore. The other settings are default.
I created my own keystore.jks file from the LetsEncrypt certificate and replaced the original keystore with the self-signed certificate.

mcc.web.enable.https=true
mcc.web.ssl.keystore.file=../conf/keystore.jks
mcc.web.ssl.keystore.password=*mysupersecretpassword*
mcc.web.ssl.keystore.type=JKS

After replacing my keystore.jks with the original file from github and setting the password to "mycontroller", https works as expected.

Hi all

Tried to run MyController with my custom LetsEncrypt certificate. To achieve this, I followed the hints in this post:
How to enable a SSL certificate?

Creating the keystore.jks file worked as expected. But when I try to run MyController, I get an error.
It seems that my keystore format is not known by MyController.

Here's the stack trace of the error:

SSLsocket creation:  java.security.UnrecoverableKeyException: Cannot recover key
java.security.UnrecoverableKeyException: Cannot recover key
	at sun.security.provider.KeyProtector.recover(KeyProtector.java:328)
	at sun.security.provider.JavaKeyStore.engineGetKey(JavaKeyStore.java:146)
	at sun.security.provider.JavaKeyStore$JKS.engineGetKey(JavaKeyStore.java:56)
	at sun.security.provider.KeyStoreDelegator.engineGetKey(KeyStoreDelegator.java:96)
	at sun.security.provider.JavaKeyStore$DualFormatJKS.engineGetKey(JavaKeyStore.java:70)
	at java.security.KeyStore.getKey(KeyStore.java:1023)
	at sun.security.ssl.SunX509KeyManagerImpl.<init>(SunX509KeyManagerImpl.java:133)
	at sun.security.ssl.KeyManagerFactoryImpl$SunX509.engineInit(KeyManagerFactoryImpl.java:70)
	at javax.net.ssl.KeyManagerFactory.init(KeyManagerFactory.java:256)
	at Acme.Serve.SSLAcceptor.init(SSLAcceptor.java:200)
	at Acme.Serve.Serve.createAcceptor(Serve.java:912)
	at Acme.Serve.Serve.init(Serve.java:769)
	at Acme.Serve.Serve.runInBackground(Serve.java:649)
	at org.jboss.resteasy.plugins.server.tjws.TJWSServletServer.start(TJWSServletServer.java:179)
	at org.jboss.resteasy.plugins.server.tjws.TJWSEmbeddedJaxrsServer.start(TJWSEmbeddedJaxrsServer.java:58)
	at org.mycontroller.standalone.StartApp.startHTTPWebServer(StartApp.java:213)
	at org.mycontroller.standalone.StartApp.startServices(StartApp.java:300)
	at org.mycontroller.standalone.StartApp.startMycontroller(StartApp.java:112)
	at org.mycontroller.standalone.StartApp.main(StartApp.java:98)
2018-03-12 22:07:51,816 ERROR [main] [org.mycontroller.standalone.StartApp:100] Unable to start application, refer error log,
java.lang.RuntimeException: java.io.IOException: java.security.UnrecoverableKeyException: Cannot recover key
	at Acme.Serve.Serve.runInBackground(Serve.java:653)
	at org.jboss.resteasy.plugins.server.tjws.TJWSServletServer.start(TJWSServletServer.java:179)
	at org.jboss.resteasy.plugins.server.tjws.TJWSEmbeddedJaxrsServer.start(TJWSEmbeddedJaxrsServer.java:58)
	at org.mycontroller.standalone.StartApp.startHTTPWebServer(StartApp.java:213)
	at org.mycontroller.standalone.StartApp.startServices(StartApp.java:300)
	at org.mycontroller.standalone.StartApp.startMycontroller(StartApp.java:112)
	at org.mycontroller.standalone.StartApp.main(StartApp.java:98)
Caused by: java.io.IOException: java.security.UnrecoverableKeyException: Cannot recover key
	at Acme.Serve.SSLAcceptor.init(SSLAcceptor.java:213)
	at Acme.Serve.Serve.createAcceptor(Serve.java:912)
	at Acme.Serve.Serve.init(Serve.java:769)
	at Acme.Serve.Serve.runInBackground(Serve.java:649)
	... 6 common frames omitted

The keystore.jks file is present. When I go back to the original keystore.jks file from github and change back the password in mycontroller.properties to mycontroller, MyController runs as expected.

I used different passwords for exporting the key to keystore.p12 (source keystore) and importing the key to keystore.jks (destination keystore).

Any hint on that problem?

Cheers
TheRaspyDev