diff --git a/xCAT-server/debian/postinst b/xCAT-server/debian/postinst
index 1454388cc..24601c1a1 100644
--- a/xCAT-server/debian/postinst
+++ b/xCAT-server/debian/postinst
@@ -31,6 +31,7 @@ case "$1" in
 	    if [ -f "/proc/cmdline" ]; then   # prevent running it during install into chroot image
 		/etc/init.d/xcatd reload
 	    fi
+            rm /tmp/xCAT-server_upgrade.tmp
 	fi
 	ln -sf /opt/xcat/sbin/xcatd /usr/sbin/xcatd
     #SHA1 has been get rid of after Squeeze released. Its functionality is also provided by Digest::SHA (which is in core).
@@ -38,7 +39,9 @@ case "$1" in
     shalocate=`find / -name "SHA.pm"`
     shalocate=${shalocate%SHA.pm}
     cd $shalocate
-    ln -s SHA.pm SHA1.pm
+    if [ ! -e SHA1.pm ];then
+        ln -s SHA.pm SHA1.pm
+    fi
     cd -
     ;;