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Updating default project template
Since 2017.2 EAP3 TeamCity supports default templates in projects. This setting was stored in a project feature of the "DefaultTemplate" type in EAP3 and EAP4, but since 2017.2 RC the project configuration schema was changed to accommodate for default templates.
To manually convert a DSL project configuration that employs the default template, you will have to delete a corresponding project feature and replace it with the defaultTemplate property assignment as follows:
2017.2 EAP3/4 DSL project configuration with a default template configured:
2017.2 DSL project configuration with the default template configured: