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Power Platform Community / Forums / Power Pages / ARRAffinity cookies of...
Power Pages
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ARRAffinity cookies of Power Pages to custom Azure Front Door

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Posted on by apangeles_ 42
Hi everyone, 
 
Can anyone help me on the ARRAffinity cookies for a Power Pages website housed in a custom Azure Front Door to change its domain value to our Azure Front Door custom domain? For example: ARRAffinity=50cf07c4923930...;Path=/;HttpOnly;Secure;Domain=customdomain.powerappsportals.com
 
What I want is the domain to be the Azure Front Door custom domain, customdomain.com 
 
I've implemented the custom domain by following this link, https://learn.microsoft.com/en-us/power-pages/configure/azure-front-door, plus another reference which it tells to turn off the CDN and WAF right after implementing the custom domain in Power Pages. 
 
I expect that after this implementation, the cookies will be transferred correctly. They are, most of them, but this ARRAffinity is not budging. What to do? 
 
Also, additional information, I've enabled session affinity in Azure Front Door which makes our website have the ASLBSA cookies. Are these cookies the replacement for ARRAffinity? And since the ARRAffinity cookies are blocked, we don't need to bother fixing them?
 
HELP!
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  • Verified answer
    Jon Unzueta Profile Picture
    Jon Unzueta 1,827 Super User 2025 Season 2 on at

    You're encountering a nuanced issue with ARRAffinity cookies in Power Pages when using Azure Front Door (AFD) with a custom domain. Here's a breakdown of what's happening and what you can do:

    🔍 Why ARRAffinity Cookie Domain Doesn’t Change

    The ARRAffinity cookie is set by Azure App Service (which underpins Power Pages) to maintain session stickiness. It is hardcoded to the App Service domain (e.g., *.azurewebsites.net or *.powerappsportals.com) and does not respect the custom domain set via Azure Front Door. This is a known limitation .

     

    Even if you configure a custom domain in AFD and Power Pages, the ARRAffinity cookie will still be scoped to the original backend domain, which causes it to be blocked by browsers due to domain mismatch.

    ✅ ASLBSA Cookies: The Modern Replacement

    You're absolutely right to ask about the ASLBSA cookies. These are:

    • Set by Azure Front Door Premium when Session Affinity is enabled.
    • Used to route requests consistently to the same backend.
    • Scoped to your custom domain, so they work correctly with AFD.

    So yes, ASLBSA cookies are effectively the replacement for ARRAffinity in this architecture.

     

    🧠 What You Should Do

    1. Ignore ARRAffinity in this setup.

      • It’s not needed if AFD session affinity is enabled and working.
      • Browsers will block it anyway due to domain mismatch.

    2. Rely on ASLBSA cookies for session stickiness.

      • Ensure your AFD origin group has Session Affinity enabled.
      • Monitor that ASLBSA cookies are being set and respected.

    3. Optional: Disable ARRAffinity at App Service level

      • If you're not using App Service directly, you can disable ARRAffinity in the App Service settings to avoid confusion.

    4. Ensure Origin Host Header is set to the custom domain in AFD.

      • This helps backend services understand the correct domain context.

    🛠️ Additional Tips

    • If you're seeing ASLBSA cookies not set on initial load, it may be due to how AFD handles the first request. This is a known behavior and may require:
      • Ensuring no caching interferes with the initial request.
      • Using custom probes to warm up instances.
    🏷️ Tag me if you have any further questions or if the issue persists.
    ✅ Click "Accept as Solution" if my post helped resolve your issue—it helps others facing similar problems.
    ❤️ Give it a Like if you found the approach useful in any way.

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