ERROR - Cannot connect to CloudCoder server

[RandomReaper]

When I run the builder, it fails to connect to the webapp, something related to ssl.

webapp log:

2018-09-26 15:14:44,680 JettyDaemon INFO  - Creating thread pool with 20 threads
2018-09-26 15:14:44,683 JettyDaemon INFO  - Starting up the server...
2018-09-26 15:14:44,683 Slf4jLog INFO  - jetty-7.x.y-SNAPSHOT
2018-09-26 15:14:44,707 Slf4jLog INFO  - Extract jar:file:/home/cloud/webapp/cloudcoderApp-v0.1.4.jar!/war/ to /home/cloud/webapp/instance-tmp-11486/jetty-0.0.0.0-8081-war-_cloudcoder-any-/webapp
2018-09-26 15:14:45,791 OutOfProcessSubmitService INFO  - Using keystore keystore.jks. password=changeit
2018-09-26 15:14:45,791 OutOfProcessSubmitService INFO  - Using keystore keystore.jks
2018-09-26 15:14:45,861 OutOfProcessSubmitService INFO  - Out of process submit service server thread started
2018-09-26 15:14:45,986 Slf4jLog INFO  - started o.e.j.w.WebAppContext{/cloudcoder,file:/home/cloud/webapp/instance-tmp-11486/jetty-0.0.0.0-8081-war-_cloudcoder-any-/webapp/},jar:file:/home/cloud/webapp/cloudcoderApp-v0.1.4.jar!/war
2018-09-26 15:14:46,033 Slf4jLog INFO  - Started SelectChannelConnector@0.0.0.0:8081 STARTING
2018-09-26 15:14:52,940 ServerTask INFO  - OOP build service: connection attempt from /127.0.0.1
2018-09-26 15:14:52,980 ServerTask ERROR - IOException waiting for connections
javax.net.ssl.SSLException: java.security.ProviderException: sun.security.pkcs11.wrapper.PKCS11Exception: CKR_ARGUMENTS_BAD
	at sun.security.ssl.Alerts.getSSLException(Alerts.java:208)
	at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1836)
	at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1799)
	at sun.security.ssl.SSLSocketImpl.handleException(SSLSocketImpl.java:1782)
	at sun.security.ssl.SSLSocketImpl.handleException(SSLSocketImpl.java:1708)
	at sun.security.ssl.AppOutputStream.write(AppOutputStream.java:124)
	at java.io.ObjectOutputStream$BlockDataOutputStream.drain(ObjectOutputStream.java:1876)
	at java.io.ObjectOutputStream$BlockDataOutputStream.setBlockDataMode(ObjectOutputStream.java:1785)
	at java.io.ObjectOutputStream.<init>(ObjectOutputStream.java:247)
	at org.cloudcoder.app.server.submitsvc.oop.WorkerTask.<init>(WorkerTask.java:71)
	at org.cloudcoder.app.server.submitsvc.oop.WorkerTaskSet.createWorker(WorkerTaskSet.java:86)
	at org.cloudcoder.app.server.submitsvc.oop.ServerTask.run(ServerTask.java:120)
	at java.lang.Thread.run(Thread.java:701)
Caused by: java.security.ProviderException: sun.security.pkcs11.wrapper.PKCS11Exception: CKR_ARGUMENTS_BAD
	at sun.security.pkcs11.P11Signature.engineSign(P11Signature.java:559)
	at java.security.Signature$Delegate.engineSign(Signature.java:1166)
	at java.security.Signature.sign(Signature.java:539)
	at sun.security.ssl.HandshakeMessage$DH_ServerKeyExchange.<init>(HandshakeMessage.java:744)
	at sun.security.ssl.ServerHandshaker.clientHello(ServerHandshaker.java:756)
	at sun.security.ssl.ServerHandshaker.processMessage(ServerHandshaker.java:225)
	at sun.security.ssl.Handshaker.processLoop(Handshaker.java:848)
	at sun.security.ssl.Handshaker.process_record(Handshaker.java:784)
	at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1012)
	at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1320)
	at sun.security.ssl.SSLSocketImpl.writeRecord(SSLSocketImpl.java:698)
	at sun.security.ssl.AppOutputStream.write(AppOutputStream.java:119)
	... 7 more
Caused by: sun.security.pkcs11.wrapper.PKCS11Exception: CKR_ARGUMENTS_BAD
	at sun.security.pkcs11.wrapper.PKCS11.C_SignFinal(Native Method)
	at sun.security.pkcs11.P11Signature.engineSign(P11Signature.java:521)
	... 18 more

builder log :

2018-09-26 15:14:52,812 Builder2Daemon INFO  - Using instance temporary directory /home/builder/builder/instance-11543
2018-09-26 15:14:52,816 ThreadGroupSecurityManager INFO  - ThreadGroupSecurityManager created
2018-09-26 15:14:52,824 Builder2Daemon INFO  - Builder starting
2018-09-26 15:14:52,824 Builder2Daemon INFO  - appHost=127.0.0.1
2018-09-26 15:14:52,824 Builder2Daemon INFO  - appPort=47374
2018-09-26 15:14:52,827 Builder2Daemon INFO  - numThreads=16
2018-09-26 15:14:52,980 Builder2Server INFO  - Failed attempt to connect to server at 1537967692980
2018-09-26 15:14:52,981 NoConnectTimer ERROR - Cannot connect to CloudCoder server
javax.net.ssl.SSLException: Received fatal alert: internal_error
	at sun.security.ssl.Alerts.getSSLException(Alerts.java:208)
	at sun.security.ssl.Alerts.getSSLException(Alerts.java:154)
	at sun.security.ssl.SSLSocketImpl.recvAlert(SSLSocketImpl.java:1902)
	at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1074)
	at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1320)
	at sun.security.ssl.SSLSocketImpl.readDataRecord(SSLSocketImpl.java:877)
	at sun.security.ssl.AppInputStream.read(AppInputStream.java:94)
	at java.io.ObjectInputStream$PeekInputStream.read(ObjectInputStream.java:2605)
	at java.io.ObjectInputStream$PeekInputStream.readFully(ObjectInputStream.java:2621)
	at java.io.ObjectInputStream$BlockDataInputStream.readShort(ObjectInputStream.java:3098)
	at java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:851)
	at java.io.ObjectInputStream.<init>(ObjectInputStream.java:348)
	at org.cloudcoder.builder2.server.Builder2Server.attemptToConnectToServer(Builder2Server.java:374)
	at org.cloudcoder.builder2.server.Builder2Server.runOnce(Builder2Server.java:290)
	at org.cloudcoder.builder2.server.Builder2Server.run(Builder2Server.java:276)
	at java.lang.Thread.run(Thread.java:701)