Cannot accept team invitation

Hi there, I am trying to create a new RTC extension. I followed the RTC Extension Workshop Lab1 to set up my development enviroment.

I tried to create a simple plug-in according to this tutorial. I created plugin, feature and update site, I have built the site, and I requested server reset by link https://localhost:9443/ccm/admin/cmd/requestReset to make sure my plugin will be deployed.

When I restarted the server and tried to log in to my repository connection, I was given this error:
CRJAZ1247E The request to the server failed. The server returned the HTTP error 400 with this error text: Bad Request.

This did not happen ever before.

Below, I attach relevant log from my workspace .metadata/.log file. Thank you very much in advance for your help!

!ENTRY com.ibm.team.process.rcp.ui 4 0 2016-11-01 23:04:48.739
!MESSAGE Error logged from Process RCP UI:
!STACK 0
com.ibm.team.repository.common.transport.TeamServiceException: CRJAZ1247E The request to the server failed. The server returned the HTTP error 400 with this error text: Bad Request.
at com.ibm.team.repository.transport.client.ClientHttpUtil.throwHttpClientError(ClientHttpUtil.java:1446)
at com.ibm.team.repository.transport.client.ClientHttpUtil.executeHttpMethod(ClientHttpUtil.java:527)
at com.ibm.team.repository.transport.client.ClientHttpUtil.executeHttpMethod(ClientHttpUtil.java:323)
at com.ibm.team.repository.transport.client.ClientHttpUtil.executeHttpMethod(ClientHttpUtil.java:221)
at com.ibm.team.repository.transport.client.ClientHttpUtil.executeHttpMethod(ClientHttpUtil.java:230)
at com.ibm.team.repository.transport.client.RestClientConnectionBase.executeMethod(RestClientConnectionBase.java:324)
at com.ibm.team.repository.transport.client.RestClientConnectionBase.doMethod(RestClientConnectionBase.java:187)
at com.ibm.team.repository.transport.client.RestClientConnectionBase.doGet(RestClientConnectionBase.java:122)
at com.ibm.team.repository.transport.client.TeamRawRestServiceClient$RawRestClientConnection.doGet(TeamRawRestServiceClient.java:96)
at sun.reflect.GeneratedMethodAccessor12.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
at java.lang.reflect.Method.invoke(Method.java:611)
at com.ibm.team.repository.client.internal.ServiceInterfaceProxy.invokeServiceCall(ServiceInterfaceProxy.java:254)
at com.ibm.team.repository.client.internal.ServiceInterfaceProxy.invoke(ServiceInterfaceProxy.java:110)
at com.ibm.team.repository.client.internal.RawRestServiceClientProxy$RestClientConnectionProxy.invoke(RawRestServiceClientProxy.java:121)
at com.sun.proxy.$Proxy10.doGet(Unknown Source)
at com.ibm.team.repository.client.internal.TeamRepository.fetchClientVersionJSONObject(TeamRepository.java:1679)
at com.ibm.team.repository.client.internal.TeamRepository.access$0(TeamRepository.java:1676)
at com.ibm.team.repository.client.internal.TeamRepository$5.run(TeamRepository.java:1747)
at com.ibm.team.repository.client.internal.TeamRepository$5.run(TeamRepository.java:1)
at com.ibm.team.repository.client.internal.TeamRepository$3.run(TeamRepository.java:1324)
at com.ibm.team.repository.common.transport.CancelableCaller.call(CancelableCaller.java:79)
at com.ibm.team.repository.client.internal.TeamRepository.callCancelableService(TeamRepository.java:1319)
at com.ibm.team.repository.client.internal.TeamRepository.checkServerVersionMatches(TeamRepository.java:1750)
at com.ibm.team.repository.client.internal.TeamRepository.internalLogin(TeamRepository.java:1512)
at com.ibm.team.repository.client.internal.TeamRepository.login(TeamRepository.java:653)
at com.ibm.team.repository.client.internal.TeamRepository.login(TeamRepository.java:627)
at com.ibm.team.process.internal.rcp.ui.LoginAction$1.run(LoginAction.java:88)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:54)