Index: /server/doc/install-howto
===================================================================
--- /server/doc/install-howto	(revision 953)
+++ /server/doc/install-howto	(revision 954)
@@ -113,4 +113,8 @@
 * Run fmtutil-sys --all, which does something that makes TeX work.
 
+* Ensure that PHP isn't broken:
+  # mkdir /tmp/sessions
+  # chmod 01777 /tmp/sessions
+
 * Reboot the machine to restore a consistent state, in case you
   changed anything.