Recently we came across an issue where all 'Update UD Agent' jobs failed with the following error:
"Failed to execute step Install Agent Basic Resources. Reason:'NoneType' object is not iterable"
After some envestigation it turned out that the file AgentsConfigurationByPlatform.xml contained multiple changes. Re-deploying the original file AgentsConfigurationByPlatform.xml from UDAgentManagement Package from Content Pack 14 resolved the issue.