After a bit of trail and error through session.flash I changed following
indx = dict(indx = search_form.vars.indx) redirect(URL(r=request, f='search', args=[lang, word], vars=indx)) to redirect(URL(r=request, f='search', args=[lang, word], vars={'indx':search_form.vars.indx})) seems working now. (On Linux, previously was on windows) But what was wrong with first approach!!!