Resolving Ajax Extenders and Net Validators Not Working After Migration to Windows Server 2019

Discover how to fix issues with Ajax extenders and .NET validators after migrating to Windows Server 2019, specifically due to ModSecurity settings.
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How to Fix Ajax Extenders and .NET Validators After Migrating to Windows Server 2019

Migrating a .NET application to a new server can be challenging, especially when key functionalities stop working. If you've recently upgraded to Windows Server 2019 and noticed that your Ajax extenders and standard validators are not functioning correctly, you're not alone. Many developers face similar hurdles during migration. This guide explores the potential causes of these issues and how to effectively resolve them.

Understanding the Problem

You've successfully migrated your .NET application from Windows Server 2012 R2 to Windows Server 2019. However, you've encountered a frustrating issue: while your code runs without any errors, Ajax extenders and standard validators have suddenly stopped working when accessed through IIS. Interestingly, they operate normally when tested on localhost or local machines.

The investigation hints at a potential misconfiguration in IIS or in the web.config file, especially given the consistent behavior of other JavaScript functions.

Key Observations

The site operates normally locally.

Ajax toolkit version is 3.0.2.

Simple JavaScript works fine without errors during debugging.

The web.config contains specific settings for validation.

Here’s an example of code that works locally but fails in the server environment:

[[See Video to Reveal this Text or Code Snippet]]

Diagnosing the Issue

After extensive research and troubleshooting, the issue was traced to a specific setting in Plesk, particularly concerning ModSecurity—a web application firewall (WAF) that protects applications by filtering HTTP requests.

What Happens with ModSecurity

Most JavaScript validations, including those used by Ajax extenders, rely on .axd resources. When ModSecurity is operating under certain filters, it may block these resources inadvertently, leading to failures in your validators and extenders.

Solution: Adjusting ModSecurity Settings

To resolve this dilemma, you need to adjust the configuration of ModSecurity within Plesk. Here’s how to do it:

Log into Plesk:

Access your Plesk control panel where your site is hosted.

Navigate to Security Settings:

Go to the “Websites & Domains” section.

Select your domain and look for the “Security” option.

Modify ModSecurity Configuration:

Find the settings for ModSecurity.

Change the filtering mode from "On" (the default) to either "Detection" or "Off".

Detection mode monitors activity without blocking anything.

Off mode disables ModSecurity entirely.

Test Your Application:

After making the adjustment, return to your web application and check if the Ajax extenders and validators are functioning as expected.

Conclusion

Migrating to a new server can unveil unexpected issues, such as the ones experienced with Ajax extender and validator functionality. Fortunately, with a little investigation and an adjustment to ModSecurity in Plesk, you can restore the full capabilities of your .NET application. Don't hesitate to seek help from communities and forums if you encounter additional hurdles along the way; troubleshooting can often lead to quicker resolutions when sharing knowledge.

Hopefully, this guide proves useful, and helps others facing similar issues in their migrations!

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Ajax extenders & Net Validators are not working after migration to Win Server 2019, .net, asp.net ajax