---
title: "Issue and solution: Web custom control not showing in designer with \"Security Error\" tooltip"
url: "https://osherove.com/blog/2003/9/10/issue-and-solution-web-custom-control-not-showing-in-designe.md"
canonical: "https://osherove.com/blog/2003/9/10/issue-and-solution-web-custom-control-not-showing-in-designe.html"
published: "2003-09-10T09:38:00"
updated: "2003-09-10T09:38:00"
tags: [".Net Original"]
author: "Roy Osherove"
description: "Tal, my wife ran into a weird situation today: She created a web custom control with very simple text output(”Hello world”), After compiling it, she created a new web application and added the compiled control to the…"
usage: "Licensed under CC BY 4.0 — reuse, quote and adapt with attribution (Roy Osherove, link to the original page)."
license: "https://creativecommons.org/licenses/by/4.0/"
---

# Issue and solution: Web custom control not showing in designer with "Security Error" tooltip

By Roy Osherove September 10, 2003 In [.Net Original](https://osherove.com/blog/category/net-original)

**Historical article** · Originally published September 10, 2003; technical details may be outdated.

Tal, my wife ran into a weird situation today:

She created a web custom control  with very simple text output(”Hello world”), After compiling it, she created a new web application and added the compiled control to the toolbox, and then dragged it into the designer. Oddly enough, the designer simply marked the control with a gray box saying “could not create control” with a tooltip saying “Security error”. Very weird. It worked on all other machines except hers.

After a full day of trial and error she discovered the reason for this. Her .Net framework security setting did not allow that control to appear on the designer. To fix it:

- Control Panel->Administrative tools - > Microsoft .Net Framework 1.x configuration
- My computer->Runtime security policy-> Click the “_Adjust Zone Security_“ link on the right pane
- Select “Make changes for this computer/user“ as you like and click next
- Select “Local Intranet“ and make sure the lower bar is at least one level below “Full trust“ level

That should solve it. Phew.

And yes, I'm a .Net developer married to a .Net developer. And you thought **your** familiy was geeky. Heh.

## More in .Net Original

[All posts in .Net Original](https://osherove.com/blog/category/net-original)

- Sep 11, 2003

    ### [Document outline](https://osherove.com/blog/2003/9/11/document-outline.html)

- Sep 10, 2003

    ### [Israeli .Net web casts - finally!](https://osherove.com/blog/2003/9/10/israeli-net-web-casts-finally.html)

- Sep 10, 2003

    ### [So, you have to live with 1.0?](https://osherove.com/blog/2003/9/10/so-you-have-to-live-with-10.html)

- Sep 8, 2003

    ### [Issues and solutions with Process and Request Identity in ASP.NET](https://osherove.com/blog/2003/9/8/issues-and-solutions-with-process-and-request-identity-in-as.html)


---

## About the author

**Roy Osherove**: Senior Solutions Architect at AWS working on AI for production and AI-driven development; author of The Art of Unit Testing and Elastic Leadership, with about 20 years of consulting and training on unit testing, TDD, team leadership and continuous delivery.

### Sites

- [RobotPaper](https://robotpaper.ai/): This blog: AI patterns and anti-patterns, AI and coding agents, and engineering leadership.
- [osherove.com](https://osherove.com): Roy's personal site. Author of The Art of Unit Testing and Elastic Leadership; consulting and training on unit testing, TDD, team leadership and continuous delivery, plus about 20 years of blog posts.
- [The Art of Unit Testing](https://www.artofunittesting.com): The Art of Unit Testing, 3rd Edition (Manning): readable, maintainable, trustworthy unit tests, plus TDD workshops in C#, JavaScript, Java and Kotlin.
- [5whys.com](https://www.5whys.com): Roy's writing on software team leadership: self-organizing teams, surviving chaos, learning mode and the Elastic Leadership model.
- [Pipeline Driven](https://pipelinedriven.org): Continuous delivery and DevOps practices: build patterns, pipeline-friendly testing, DevOps metrics and enterprise DevOps.
- [Elastic Leadership](https://www.elasticleadership.com): Elastic Leadership, Roy's framework for software team leaders (survival, learning and self-organizing modes).

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### Contact

- Contact form: https://forms.gle/jQSx5KoXvrVA1JCK7

### License

Licensed under CC BY 4.0 — reuse, quote and adapt with attribution (Roy Osherove, link to the original page). License: https://creativecommons.org/licenses/by/4.0/