How to solve an existence of XML namespace in WPF application?

The exception like “WPF DataGrid (SfDataGrid) does not exist in XML namespace” will occurs when Syncfusion assemblies referred in the application differed from Application’s Target Framework or different versions of Syncfusion assemblies referred in the same project.

Using same version of Syncfusion assembly in project to solve - Error:  Assembly 'X' uses 'Y' which has a higher version than referenced assembly ‘Y'

You have to refer the same version Syncfusion assemblies in the application. You can find the version information from the properties of assembly as below,

Otherwise,

Error CS1705 Assembly 'X' uses 'Y' which has a higher version than referenced assembly ‘Y'

Using Syncfusion assembly based on target framework to solve - Control does not exist in XML namespace

If you are developing application in 4.5.1 framework, then you should use the framework version of Syncfusion assembly. You can check this from Syncfusion assembly version (14.4451.0.15). For example,

• Version 14.4451.0.15 – Denotes the assemble can be used in 4.5.1 target framework application.
• Version 14.4450.0.15 – Denotes the assemble can be used in 4.5 target framework application.
• Version 14.4400.0.15 – Denotes the assemble can be used in 4.0 target framework application.
• Version 14.4350.0.15 – Denotes the assemble can be used in 3.5 target framework application.

As in the below code screen shot, Application target framework and all Syncfusion assemblies should target same framework version.