Merge pull request #642 from pveentjer/0.5.0-rc.1
added explanation for ubuntu 8 and sudo -n problem
diff --git a/docs/start/known-issues.md b/docs/start/known-issues.md
index f30e503..ee2523a 100644
--- a/docs/start/known-issues.md
+++ b/docs/start/known-issues.md
@@ -15,3 +15,13 @@
*Fix*: is [Pull #600](https://github.com/brooklyncentral/brooklyn/pull/600); you may also want to run with `brooklyn.jclouds.aws-ec2.user=root` if subsequent commands give permission errors.
*Versions Affected*: 0.5.0-M2
+
+### Unable to Provision Ubuntu 8 VMs
+
+*Symptom: Brooklyn fails to provision Ubuntu 8 VMs (e.g. in aws-ec2) with the following error 'Cannot insert the iptables rule for port 22. Error: sudo: illegal option `-n''.
+
+*Cause: Ubuntu 8 is too old; the sudu command doesn't support the -n setting.
+
+*Workaround: Choose Ubuntu 10 or higher.
+
+*Versions Affected*: 0.5.0-M2
