getSiteByKey error

Hello.  I started seeing problems with a Jahia site recently.  It has run
smoothly all summer.  No changes were made in the past month or so, but
about 10 days ago, I started seeing an error which causes the site to
display only the error page (see stack trace excerpt below).

It's a nullPointerterException at the call to getSiteByKey.  I'm trying to
find what could be causing this.  Any ideas?  (I've seen this issue once
before and I posted it here (over a year ago) - someone suggested that I'm
losing connections somewhere.)

thanks
chris


81481259 [Thread-23] ERROR - Throwable Exception caught in Jahia servlet :
java.lang.NullPointerException
java.lang.NullPointerException
	at
org.jahia.services.sites.JahiaSitesBaseService.getSiteByKey(Ljava.lang.Strin
g;)Lorg.jahia.services.sites.JahiaSite;(JahiaSitesBaseService.java:177)
	at
org.jahia.params.ParamBean.getDefaultSite()Lorg.jahia.services.sites.JahiaSi
te;(ParamBean.java:1677)
	at
org.jahia.params.ParamBean.getSiteInfos(Ljavax.servlet.http.HttpSession;)V(P
aramBean.java:1608)
	at
org.jahia.params.ParamBean.<init>(Ljavax.servlet.http.HttpServletRequest;Lja
vax.servlet.http.HttpServletResponse;Ljavax.servlet.ServletContext;Lorg.jahi
a.settings.SettingsBean;JI)V(ParamBean.java:444)
	at
org.jahia.bin.Jahia.service(Ljavax.servlet.http.HttpServletRequest;Ljavax.se
rvlet.http.HttpServletResponse;)V(Optimized Method)
	at
javax.servlet.http.HttpServlet.service(Ljavax.servlet.ServletRequest;Ljavax.
servlet.ServletResponse;)V(Optimized Method)
	at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Ljavax.serv
let.ServletRequest;Ljavax.servlet.ServletResponse;)V(ApplicationFilterChain.
java:247)