Problem with HUP occurs after upgrade from 2.1.5

[Ben Thompson]

Hi

I have a server running 2.1.5 which has been running happily for a
long time with the same config. However, I recenlty tried upgrading to
2.1.8 and found that after HUP the server dies :-

Mon Mar  8 22:05:58 2010 : Info: Loaded virtual server inner-tunnel
Mon Mar  8 22:05:58 2010 : Info: Loaded virtual server <default>
Mon Mar  8 22:05:59 2010 : Error: ASSERT FAILED modcall.c[106]: (p->type > MOD_SINGLE) && (p->type <= MOD_POLICY)

I also tried 2.1.6 and this also had the problem. Can anyone advise
what this error means?

Thanks

Ben