Creating an issue via REST API causes NullPointerException

{"project": {"key": "ODE"}, "issuetype": {"name": "Release"}, "reporter": {"name": "mhowells"}, "assignee": {"name": "mhowells"}, "summary": "XXX 9.9.9"}

0:0:0:0:0:0:0:1 i868x2429x1 minion [20/Feb/2014:14:28:36 +1100] "POST http://localhost:2990/jira/rest/api/latest/issue HTTP/1.1" - - - - "python-requests/2.2.1 CPython/2.7.5 Darwin/13.0.2" "d4xvk5"
0:0:0:0:0:0:0:1 o868x2429x1 minion [20/Feb/2014:14:28:36 +1100] "POST http://localhost:2990/jira/rest/api/latest/issue HTTP/1.1" 500 55 0.0840 - "python-requests/2.2.1 CPython/2.7.5 Darwin/13.0.2" "d4xvk5"
	___ Request _____________________________________________________
	Request HTTP Headers : 
		host=localhost:2990
		content-length=154
		accept-encoding=gzip, deflate, compress
		accept=*/*
		user-agent=python-requests/2.2.1 CPython/2.7.5 Darwin/13.0.2
		content-type=application/json
		authorization=Basic bWluaW9uOkhlcmUySGVscA==
	Request Attributes : 
		os_securityfilter_already_filtered=true
		com.atlassian.jira.web.filters.JiraPostEncodingFilter_alreadyfiltered=true
		com.atlassian.seraph.auth.LoginReason=OK
		com.newrelic.agent.TRANSACTION_NAME=/rest/api/*
		jira.request.id=868x2429x1
		jira.webwork.cleanup=false
		atlassian.core.seraph.original.url=/rest/api/latest/issue
		com.atlassian.labs.botkiller.BotKillerFilter=true
		com.atlassian.jira.web.filters.JiraFirstFilter_alreadyfiltered=true
		com.atlassian.jira.web.filters.JiraDecoratingFilter_alreadyfiltered=true
		com.atlassian.gzipfilter.GzipFilter_already_filtered=true
		jira.request.start.millis=1392866916213
		loginfilter.already.filtered=true
		com.atlassian.johnson.filters.Johnson503Filter_already_filtered=true
		com.atlassian.jira.web.filters.accesslog.AccessLogFilter_already_filtered=true
		com.atlassian.jira.security.login.LoginManager.LoginResult=com.atlassian.jira.bc.security.login.LoginResultImpl@7320f478[reason=OK,loginInfo=com.atlassian.jira.bc.security.login.LoginInfoImpl@78922d54[lastLoginTime=1392866916288,previousLoginTime=1392866916193,loginCount=87,currentFailedLoginCount=0,totalFailedLoginCount=<null>,lastFailedLoginTime=<null>,elevatedSecurityCheckRequired=false,maxAuthenticationAttemptsAllowed=3],userName=minion,deniedReasons=[]]
		jira.request.username=minion
		jira.request.assession.id=d4xvk5
		os_authstatus=success
		com.atlassian.jira.security.xsrf.XsrfTokenAdditionRequestFilter_already_filtered=true
		com.atlassian.prettyurls.filter.PrettyUrlsSiteMeshFilter=true
		jira.xsrf.set.cookie.pending=BJTN-KXGI-ESGW-T2KJ|aff9dd19966106083be98697b8f16a51e67a9501|lin
		os_authTypeDefault=any
		page.builder=com.atlassian.jira.web.pagebuilder.DefaultPageBuilder@44de23a3
	Request Data (total 154 bytes) : 

{"project": {"key": "ODE"}, "issuetype": {"name": "Release"}, "reporter": {"name": "mhowells"}, "assignee": {"name": "mhowells"}, "summary": "XXX 9.9.9"}
				___ Response ____________________________________________________
	Response HTTP Headers : 
		X-AUSERNAME=minion
		Cache-Control=no-cache, no-store, no-transform
		Content-Type=application/json
	Response Data (total 55 bytes) : 

{"errorMessages":["Internal server error"],"errors":{}}