ASP.NET Web Forms License Validation Issues

Curtis Chau

Updated: July 6, 2026

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  # ASP.NET Web Forms License Validation Issues 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>`: ```xml <system.web> <httpRuntime targetFramework="4.7.2" /> </system.web> ``` If `httpRuntime` already exists but lacks `targetFramework`, add the attribute: ```xml <httpRuntime maxRequestLength="4096" executionTimeout="110" targetFramework="4.7.2" /> ``` Use `targetFramework="4.7.2"` or a higher value. The minimum value that enables TLS 1.2 by default is `"4.6"` (using 4.7 or higher also enables `SystemDefaultTlsVersions`).

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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>

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" />

Use targetFramework="4.7.2" or a higher value. The minimum value that enables TLS 1.2 by default is "4.6" (using 4.7 or higher also enables SystemDefaultTlsVersions).

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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