Below are two ways to configure and run a debugger in order to debug a TIBCO Spotfire custom extension in the TIBCO Spotfire Analyst client.​

1. Open the solution in Visual Studio and build the project.
2. Open Package Builder > Add the Custom Extension > Validate and Save 
3. Go back to Visual Studio and in the Solution Explorer, right-click the project, and then select Properties.
4. Select the Debug tab. The Debug dialog is displayed.
5. Click Start external program, and then browse to the location of the Starter Spotfire executable.The special Spotfire executable (Spotfire.Dxp.exe) is located in the Starter directory in the Spotfire SDK distribution. 
6. From the Visual Studio toolbar, click Start.

1. Open the custom extension in Visual Studio and build the project. Insert break points (Ex: In the CustomTool Example you can insert a break point in the PageTool.cs or any other)
2. Open Package Builder > Add the Custom Extension > Validate and Save > Run the Configuration
3. Now in Visual Studio, Goto Debug > Attach to Process > Spotfire.Dxp.exe
4. In the Spotfire analyst, execute the tool and now you should be able to debug the code and hit any breakpoints inserted in the code.

• https://docs.tibco.com/pub/sfire_dev/area/doc/html/GUID-4AA5D61A-1EE1-4760-82A7-C7FF5DD88C29.html