Today, We have downloaded a report from Report Manager, If try to open that in Visual Studio IDE, it throws error as “Deserialization failed: The ‘DataType’ attribute is not declared. Line 1279, position 20.”. (refer the exhibit below)
When I reviewed the code (By Click Edit code or View code), I found that DataType attribute was not recognized by report render engine. so I guess DataType was an attribute of report element and it has introduced by VS2008 IDE, this has not been corrected and performing some action in the report designer while add the DataType attribute which is not allowed in the schema.
To fix this issue, I have replaced the DataType with blank as mentioned in the screenshot below
after replaced it, when I check the report via designer, it render the report content properly.
I faced this issues with float datatype, you may experience with anyother datatype like Integer, Strings, Date, etc., you can follow the same approach. Note that, before try this approach, backup your report to avoid any surprises and then try this. Hope this may helps you!