error in my design

Question

Could not find type 'DVLD.ctrPersonInformation'. Please make sure that the assembly that contains this type is referenced. If this type is a part of your development project, make sure that the project has been successfully built using settings for your c

Answer 1

Hi @Raneem kamel

According to the Windows Forms designer error documentation, this error usually means the designer cannot find the referenced type because the required assembly or project reference is missing, or the control/project has not been built successfully yet. Microsoft specifically recommends checking that the type and any dependent assemblies are referenced, then rebuilding the solution. If the control has already been built, you can also add the reference manually from the References or Dependencies node in Solution Explorer.

https://learn.microsoft.com/en-us/dotnet/desktop/winforms/controls-design/designer-errors?view=netdesktop-9.0#could-not-find-type-type-name

You may want to check:

• DVLD.ctrPersonInformation exists in a referenced project or assembly
• the project/solution builds successfully
• cleaning and rebuilding the solution helps
• the control was renamed, moved, or its namespace changed

Also it would be great if you can provide a bit more context?

1. Is ctrPersonInformation a custom UserControl in the same solution?
2. Does the full solution build successfully?
3. Did this start after renaming files, changing namespaces, or moving the control to another project?
4. Is the error happening only in the designer, or also at compile time?
5. Can you share where DVLD.ctrPersonInformation is defined and how it is referenced?

I hope this helps. If you found my response helpful or informative, I would greatly appreciate it if you could follow this guidance or provide feedback.

Thank you. 

Answer 2

The error indicates that the Windows Forms Designer cannot find the type DVLD.ctrPersonInformation at design time. This is a design-time reference problem, not just a runtime one.

To fix it, follow these steps in order:

1. Build the project that contains DVLD.ctrPersonInformation:
   • In Visual Studio, select Build > Build Solution.
   • Ensure the build succeeds without errors.
2. Ensure the project/assembly that defines DVLD.ctrPersonInformation is referenced:
   • In the project where the form is designed, open Solution Explorer.
   • Right‑click References (or Dependencies in SDK‑style projects) and choose Add Reference….
   • Select the project or assembly that contains DVLD.ctrPersonInformation and add it.
3. Confirm the type name and namespace:
   • Open the code file where ctrPersonInformation is defined.
   • Verify the namespace is DVLD and the class name is exactly ctrPersonInformation (including case).
   • In the designer file (.Designer.cs), ensure the fully qualified name matches (DVLD.ctrPersonInformation).
4. Clean and rebuild:
   • Use Build > Clean Solution, then Build > Rebuild Solution.
   • Close and reopen the designer if it was open.

If ctrPersonInformation is a user control in the same solution, the most common cause is that its project has not been built yet or the reference between projects is missing.

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References:

• Windows Forms Designer error page