ASP.NET Web Forms License Validation Issues

Updated:June 9, 2026

IronPDF license validation fails in an ASP.NET Web Forms application. HTTP requests to the licensing server are rejected due to an unsupported TLS version.

ASP.NET Web Forms applications default to TLS 1.0 when httpRuntime is not configured with a targetFramework attribute. The IronPDF licensing server requires TLS 1.2, which .NET Framework 4.6.1 and later support, but only when httpRuntime targetFramework is set to that version or higher. The <compilation targetFramework> element alone is not sufficient. httpRuntime targetFramework is what controls TLS protocol selection during outbound HTTP requests.

Solution

Add or update the httpRuntime element in Web.config.

If httpRuntime is absent, add it inside <system.web>:

<system.web>
  <httpRuntime targetFramework="4.7.2" />
</system.web>

<system.web>
  <httpRuntime targetFramework="4.7.2" />
</system.web>

XML

If httpRuntime already exists but lacks targetFramework, add the attribute:

<httpRuntime maxRequestLength="4096" executionTimeout="110" targetFramework="4.7.2" />

<httpRuntime maxRequestLength="4096" executionTimeout="110" targetFramework="4.7.2" />

XML

Use targetFramework="4.7.2" or a higher value. The minimum value that enables TLS 1.2 is "4.6.1".

Curtis Chau

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Technical Writer

Curtis Chau holds a Bachelor’s degree in Computer Science (Carleton University) and specializes in front-end development with expertise in Node.js, TypeScript, JavaScript, and React. Passionate about crafting intuitive and aesthetically pleasing user interfaces, Curtis enjoys working with modern frameworks and creating well-structured, visually appealing manuals.

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