We already answered to the support ticket you have posted which includes this issue and in which you have provided some code snippets demonstrating the problem. For your convenience and to make the answer available to the community in case somebody experiences the same problem I will go ahead and paste our answer here as well:
I created a sample page based on the code snippets you have sent us and was able to reproduce the issue you mention.
It could be resolved by replacing the
(as the RadDockLayout maintains the proper positioning of the RadDocks)
- this is the reason for experiencing an "Invalid JSON primitive error"
as the docks are duplicated at postback/callback in your case.
Let us know if the above suggestion cannot help you resolve the issue.
the Telerik team
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