Editing the configuration of an existing custom field when selecting "all issue types" causes a crash. Choosing all of the issue:

java.lang.ClassCastException: java.lang.String
at com.atlassian.jira.util.ofbiz.GenericValueUtils.transformToStrings
(GenericValueUtils.java:52)
at com.atlassian.jira.web.action.admin.customfields.ManageConfigurationScheme.doDefault
(ManageConfigurationScheme.java:106)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at webwork.util.InjectionUtils$DefaultInjectionImpl.invoke(InjectionUtils.java:61)
at webwork.util.InjectionUtils.invoke(InjectionUtils.java:52)
at webwork.action.ActionSupport.invokeCommand(ActionSupport.java:417)
at webwork.action.ActionSupport.execute(ActionSupport.java:146)
at com.atlassian.jira.action.JiraActionSupport.execute(JiraActionSupport.java:57)
at webwork.dispatcher.GenericDispatcher.executeAction(GenericDispatcher.java:132)
at com.atlassian.jira.web.dispatcher.JiraServletDispatcher.service
(JiraServletDispatcher.java:185)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter

The workaround for this issue is to select the issue types to which the custom field should be associated, rather than to select "all issue types". Alternatively, rather than to edit, deleting and re-adding the custom field type likewise avoids the problem.

There is a patch attached to this issue to fix this, see the comment for installation instructions.