title: TeamCity Build Agent won't upgrade
body: <p>We are trying to setup a build agent and every time we start it the log shows the following messages:</p>
  
  <pre><code>[2012-09-18 12:52:01,805]   INFO -    jetbrains.buildServer.AGENT - Starting agent shutdown sequence, reason: Restart agent, failed to download upgrade from server 
  [2012-09-18 12:52:01,821]   INFO -    jetbrains.buildServer.AGENT - Host configuration for downloading updates: HostConfiguration[host=http://localhost:8000] 
  [2012-09-18 12:52:01,821]   INFO -    jetbrains.buildServer.AGENT - Downloading http://localhost:8000/update/teamcity-agent.xml ==&gt; E:\buildAgent\temp\m8a1mAwTuLIngev3yRUMPUuaYWZFmMSh 
  [2012-09-18 12:52:01,849]   INFO -    jetbrains.buildServer.AGENT - Downloading http://localhost:8000/update/plugins/agentSystemInfo.zip ==&gt; E:\buildAgent\update\plugins\agentSystemInfo.zip 
  [2012-09-18 12:52:01,880]   INFO -    jetbrains.buildServer.AGENT - Downloading http://localhost:8000/update/plugins/amazonEC2.zip ==&gt; E:\buildAgent\update\plugins\amazonEC2.zip 
  [2012-09-18 12:52:01,921]   INFO -    jetbrains.buildServer.AGENT - Downloading http://localhost:8000/update/plugins/ant.zip ==&gt; E:\buildAgent\update\plugins\ant.zip 
  [2012-09-18 12:52:02,056]   INFO -    jetbrains.buildServer.AGENT - Downloading http://localhost:8000/update/plugins/antPlugin.zip ==&gt; E:\buildAgent\update\plugins\antPlugin.zip 
  [2012-09-18 12:52:02,078]   INFO -    jetbrains.buildServer.AGENT - Downloading http://localhost:8000/update/plugins/assembly-info-patcher.zip ==&gt; E:\buildAgent\update\plugins\assembly-info-patcher.zip 
  [2012-09-18 12:52:02,098]   INFO -    jetbrains.buildServer.AGENT - Downloading http://localhost:8000/update/plugins/clearcase-agent.zip ==&gt; E:\buildAgent\update\plugins\clearcase-agent.zip 
  [2012-09-18 12:52:02,106]   INFO -    jetbrains.buildServer.AGENT - Downloading http://localhost:8000/update/plugins/commandLineRunner.jar ==&gt; E:\buildAgent\update\plugins\commandLineRunner.jar 
  [2012-09-18 12:52:02,118]   INFO -    jetbrains.buildServer.AGENT - Downloading http://localhost:8000/update/plugins/coveragePlugin.zip ==&gt; E:\buildAgent\update\plugins\coveragePlugin.zip 
  [2012-09-18 12:52:02,151]   INFO -    jetbrains.buildServer.AGENT - Downloading http://localhost:8000/update/plugins/crashDetector.zip ==&gt; E:\buildAgent\update\plugins\crashDetector.zip 
  [2012-09-18 12:52:02,163]   INFO -    jetbrains.buildServer.AGENT - Downloading http://localhost:8000/update/plugins/cvsAgent.zip ==&gt; E:\buildAgent\update\plugins\cvsAgent.zip 
  [2012-09-18 12:52:02,183]   INFO -    jetbrains.buildServer.AGENT - Downloading http://localhost:8000/update/plugins/dotCover.zip ==&gt; E:\buildAgent\update\plugins\dotCover.zip 
  [2012-09-18 12:52:02,308]   INFO -    jetbrains.buildServer.AGENT - Downloading http://localhost:8000/update/plugins/dotNetPlugin.zip ==&gt; E:\buildAgent\update\plugins\dotNetPlugin.zip 
  [2012-09-18 12:52:03,830]   INFO - agent.impl.AgentPortFileWriter - Delete agent runtime file from E:\buildAgent\logs\buildAgent.port 
  [2012-09-18 12:52:03,831]   INFO -    jetbrains.buildServer.AGENT - Unregistering from build server: 5 
  </code></pre>
  
  <p>Has anyone seen anything like this before?  We've looked at the server logs and aren't seeing anything on them to indicate what could be wrong.</p>