Sitefinity 5.3 Hotfix 1 has just been released.
It provides a fix for a randomly reproducible exception when using Sitefinity Module Builder:
The exception message is:
Expected instance of type Telerik.Sitefinity.DynamicTypes.Model.YourModuleType
Parameter name: component
Actual value was Telerik.Sitefinity.DynamicTypes.Model.YourModuleType
It also offers and improved overall system stability in areas where potential deadlock issues can occur leading to unresponsive site. For more information about these system stability improvements please check our Sitefinity 5.4 Hotfix 2 release notes.