1. i generated a selfsigned certificate/private key in DER format
2. placed certificate file to
/home/user/.prosysopc/prosys-opc-ua-simulation-server/USERS_PKI/CA/certs
/home/user/.prosysopc/prosys-opc-ua-simulation-server/PKI/CA/certs
3. checked that certificate for my user is trusted in certificates tab of prosys server
4. tried to connect to prosys using params:
endpoint with certificate for user/application – one which i generated on step 1
message security level – MessageSecurityMode = Sign
user = UserTokenType = certificate

5. received general error like

23:18:49.976 [milo-netty-event-loop-4] DEBUG org.eclipse.milo.opcua.stack.client.transport.http.OpcHttpTransport – channelCreated(): [id: 0x6b0b3ba9]
23:18:49.977 [milo-netty-event-loop-4] DEBUG org.eclipse.milo.opcua.stack.client.transport.http.OpcHttpTransport – channelAcquired(): [id: 0x6b0b3ba9, L:/127.0.0.1:46828 – R:pc120/127.0.0.1:53443]
23:18:50.079 [milo-netty-event-loop-4] DEBUG org.eclipse.milo.opcua.stack.client.transport.http.OpcClientHttpCodec – encoding: CreateSessionRequest(requestHeader=RequestHeader(authenticationToken=NodeId{ns=0, id=0}, timestamp=DateTime{utcTime=132457979299730000, javaDate=Mon Sep 28 23:18:49 MSK 2020}, requestHandle=0, returnDiagnostics=0, auditEntryId=null, timeoutHint=5000, additionalHeader=null), clientDescription=ApplicationDescription(applicationUri=urn:xxx:client, productUri=client product uri not configured, applicationName=LocalizedText{text=qubicon opc-ua client, locale=en}, applicationType=Client, gatewayServerUri=null, discoveryProfileUri=null, discoveryUrls=null), serverUri=null, endpointUrl=opc.https://pc120:53443/OPCUA/SimulationServer, sessionName=UaSession:qubicon opc-ua client:1601324329973, clientNonce=ByteString{bytes=[-107, , 105]}, clientCertificate=ByteString{bytes=[48, -126,,115]}, requestedSessionTimeout=120000.0, maxResponseMessageSize=0)
23:18:50.082 [milo-netty-event-loop-4] DEBUG io.netty.handler.ssl.util.InsecureTrustManagerFactory – Accepting a server certificate: CN=pc120
23:18:50.099 [milo-netty-event-loop-4] DEBUG io.netty.handler.ssl.SslHandler – [id: 0x6b0b3ba9, L:/127.0.0.1:46828 – R:pc120/127.0.0.1:53443] HANDSHAKEN: protocol:TLSv1.2 cipher suite:TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
23:18:50.104 [milo-netty-event-loop-4] DEBUG org.eclipse.milo.opcua.stack.client.transport.http.OpcHttpTransport – channelReleased(): [id: 0x6b0b3ba9, L:/127.0.0.1:46828 – R:pc120/127.0.0.1:53443]
23:18:50.104 [milo-shared-thread-pool-0] DEBUG org.eclipse.milo.opcua.stack.client.UaStackClient – Received ServiceFault request=CreateSessionRequest requestHandle=0, result=StatusCode{name=Bad_InternalError, value=0x80020000, quality=bad}
23:18:50.153 [milo-shared-thread-pool-0] DEBUG org.eclipse.milo.opcua.sdk.client.SessionFsm – [0] CreateSession failed: UaServiceFaultException: status=Bad_InternalError, message=An internal error occurred as a result of a programming or configuration error.

6. looked at prosys logs at /home/user/.prosysopc/prosys-opc-ua-simulation-server/log/simulationserver.log

09/28/2020 23:18:49.977 INFO [I/O dispatcher 416] com.prosysopc.ua.stack.transport.b.c [] – connected: [/fe80:0:0:0:28ee:79ff:fe26:9ff3%vethbf2a719:53443, /0:0:0:0:0:0:0:1%lo:53443, /127.0.0.1:53443, /fe80:0:0:0:a423:31ff:fead:e833%vethe811ffc:53443, /fe80:0:0:0:a81a:e1ff:feed:2b68%vethdcafd63:53443, /192.168.220.1:53443, /fe80:0:0:0:3c4b:94ff:fecd:3bd4%veth503b270:53443, /192.168.100.4:53443, /172.22.0.1:53443, /172.23.0.1:53443, /172.17.0.1:53443, /fe80:0:0:0:14ec:6ff:fe82:a0d9%vethfeea0b1:53443, /172.18.0.1:53443, /172.19.0.1:53443, /fe80:0:0:0:489a:63ff:fef7:4a8%vethab3ba47:53443, /fe80:0:0:0:3026:b3ff:fe8d:a6c9%vethd62ce93:53443, /fe80:0:0:0:42:efff:fea2:be9c%docker_gwbridge:53443, /fe80:0:0:0:4449:d5f9:b766:69d1%enp4s0:53443, /192.168.100.241:53443, /172.27.0.1:53443, /fe80:0:0:0:5061:68ff:fee0:215b%veth55d5c29:53443] /127.0.0.1 /127.0.0.1 context=[ioSession=127.0.0.1:53443127.0.0.1:46828[ACTIVE][r:][ACTIVE][r][NOT_HANDSHAKING][0][0][0]] socketTimeout=0
09/28/2020 23:18:50.100 INFO [I/O dispatcher 416] com.prosysopc.ua.stack.transport.b.e [] – HttpsServerEndpointHandler.handle(): singleSecureChannel.setConnection(127.0.0.1:53443127.0.0.1:46828)
09/28/2020 23:18:50.101 ERROR [I/O dispatcher 416] com.prosysopc.ua.stack.cert.c [] – error while validating certificates
java.lang.NullPointerException: null
at com.prosysopc.ua.stack.cert.c.a(SourceFile:126) [ui-javafx-5.0.2-242.jar:5.0.2-242]
at com.prosysopc.ua.UaApplication.a(SourceFile:399) [ui-javafx-5.0.2-242.jar:5.0.2-242]
at com.prosysopc.ua.server.aq.a(SourceFile:145) [ui-javafx-5.0.2-242.jar:5.0.2-242]
at com.prosysopc.ua.server.aq$1.onCreateSession(SourceFile:605) [ui-javafx-5.0.2-242.jar:5.0.2-242]
at com.prosysopc.ua.server.ab.h(SourceFile:521) [ui-javafx-5.0.2-242.jar:5.0.2-242]
at com.prosysopc.ua.server.ab.a(SourceFile:855) [ui-javafx-5.0.2-242.jar:5.0.2-242]
at com.prosysopc.ua.server.af.onCreateSession(SourceFile:136) [ui-javafx-5.0.2-242.jar:5.0.2-242]
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?]
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:?]
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
at java.lang.reflect.Method.invoke(Method.java:566) ~[?:?]
at com.prosysopc.ua.stack.a.h$1.c(SourceFile:114) [ui-javafx-5.0.2-242.jar:5.0.2-242]
at com.prosysopc.ua.stack.a.h.c(SourceFile:235) [ui-javafx-5.0.2-242.jar:5.0.2-242]
at com.prosysopc.ua.stack.transport.b.e.a(SourceFile:202) [ui-javafx-5.0.2-242.jar:5.0.2-242]
at com.prosysopc.ua.stack.transport.b.e.a(SourceFile:177) [ui-javafx-5.0.2-242.jar:5.0.2-242]
at com.prosysopc.ua.stack.transport.b.i.run(SourceFile:215) [ui-javafx-5.0.2-242.jar:5.0.2-242]
at com.prosysopc.ua.stack.transport.b.e.a(SourceFile:130) [ui-javafx-5.0.2-242.jar:5.0.2-242]
at com.prosysopc.ua.stack.transport.b.e.handle(SourceFile:48) [ui-javafx-5.0.2-242.jar:5.0.2-242]