NPE when creating new issue

When creating a new issue (after clicking "Create" button) I get this exception. I am not sure if all our users get it (but will know it in a few hours on all projects.

2003-10-06 09:36:14,357 ERROR [web.action.issue.CreateIssueDetails] Exception in doExecute() An unknown exception occured while executing FunctionProvider: com.atlassian.jira.workflow.function.issue.UpdateIssueFieldFunction
com.opensymphony.workflow.InternalWorkflowException: An unknown exception occured while executing FunctionProvider: com.atlassian.jira.workflow.function.issue.UpdateIssueFieldFunction
at com.opensymphony.workflow.AbstractWorkflow.executeFunction(AbstractWorkflow.java:934)
at com.opensymphony.workflow.AbstractWorkflow.transitionWorkflow(AbstractWorkflow.java:1107)
at com.opensymphony.workflow.AbstractWorkflow.initialize(AbstractWorkflow.java:366)
at com.atlassian.jira.issue.IssueUtils.createIssue(IssueUtils.java:80)
at com.atlassian.jira.issue.IssueUtils.createIssue(IssueUtils.java:65)
at com.atlassian.jira.web.action.issue.CreateIssueDetails.doExecute(CreateIssueDetails.java:290)
at webwork.action.ActionSupport.execute(ActionSupport.java:149)
at com.atlassian.jira.action.JiraActionSupport.execute(JiraActionSupport.java:44)
at webwork.dispatcher.GenericDispatcher.executeAction(GenericDispatcher.java:131)
at webwork.dispatcher.ServletDispatcher.service(ServletDispatcher.java:165)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:336)
at com.evermind._ie.doFilter(.:59)
at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:129)
at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:61)
at com.atlassian.jira.web.filters.SitemeshExcludePathFilter.doFilter(SitemeshExcludePathFilter.java:39)
at com.evermind._ic.doFilter(.:16)
at com.atlassian.core.security.SecurityFilter.doFilter(SecurityFilter.java:170)
at com.evermind._ic.doFilter(.:20)
at com.atlassian.core.security.LoginFilter.doFilter(LoginFilter.java:190)
at com.evermind._ic.doFilter(.:20)
at com.atlassian.util.profiling.filters.ProfilingFilter.doFilter(ProfilingFilter.java:132)
at com.evermind._ic.doFilter(.:20)
at com.atlassian.jira.web.filters.AppConsistencyFilter.doFilter(AppConsistencyFilter.java:92)
at com.evermind._ic.doFilter(.:20)
at com.atlassian.jira.web.filters.EncodingFilter.doFilter(EncodingFilter.java:53)
at com.evermind._deb._lnc(.:376)
at com.evermind._deb._wmb(.:170)
at com.evermind._co._wbb(.:581)
at com.evermind._co._fs(.:189)
at com.evermind._bt.run(.:62)

Root cause:
java.lang.NullPointerException
at com.atlassian.jira.workflow.function.issue.UpdateIssueFieldFunction.execute(UpdateIssueFieldFunction.java:35)
at com.opensymphony.workflow.AbstractWorkflow.executeFunction(AbstractWorkflow.java:930)
at com.opensymphony.workflow.AbstractWorkflow.transitionWorkflow(AbstractWorkflow.java:1107)
at com.opensymphony.workflow.AbstractWorkflow.initialize(AbstractWorkflow.java:366)
at com.atlassian.jira.issue.IssueUtils.createIssue(IssueUtils.java:80)
at com.atlassian.jira.issue.IssueUtils.createIssue(IssueUtils.java:65)
at com.atlassian.jira.web.action.issue.CreateIssueDetails.doExecute(CreateIssueDetails.java:290)
at webwork.action.ActionSupport.execute(ActionSupport.java:149)
at com.atlassian.jira.action.JiraActionSupport.execute(JiraActionSupport.java:44)
at webwork.dispatcher.GenericDispatcher.executeAction(GenericDispatcher.java:131)
at webwork.dispatcher.ServletDispatcher.service(ServletDispatcher.java:165)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:336)
at com.evermind._ie.doFilter(.:59)
at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:129)
at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:61)
at com.atlassian.jira.web.filters.SitemeshExcludePathFilter.doFilter(SitemeshExcludePathFilter.java:39)
at com.evermind._ic.doFilter(.:16)
at com.atlassian.core.security.SecurityFilter.doFilter(SecurityFilter.java:170)
at com.evermind._ic.doFilter(.:20)
at com.atlassian.core.security.LoginFilter.doFilter(LoginFilter.java:190)
at com.evermind._ic.doFilter(.:20)
at com.atlassian.util.profiling.filters.ProfilingFilter.doFilter(ProfilingFilter.java:132)
at com.evermind._ic.doFilter(.:20)
at com.atlassian.jira.web.filters.AppConsistencyFilter.doFilter(AppConsistencyFilter.java:92)
at com.evermind._ic.doFilter(.:20)
at com.atlassian.jira.web.filters.EncodingFilter.doFilter(EncodingFilter.java:53)
at com.evermind._deb._lnc(.:376)
at com.evermind._deb._wmb(.:170)
at com.evermind._co._wbb(.:581)
at com.evermind._co._fs(.:189)
at com.evermind._bt.run(.:62)
leadName = dominikr
User: dominikr