Issue loading B2CLogin pages correctly

Question

Issue loading B2CLogin pages correctly

Sam 1

Hello,

This is an issue we have had for some time.

We use two websites that use the b2clogin to login - this is our finance system and a portal for NCFE.

On our network, these pages do not load correctly. The background of the website seems to bring itself forward, blocking buttons or information that you may need to actually log in. The only work around we have had for this is to use inspect element and delete the background of the website to get it to work. I will leave examples below of what they look like.

We use Sophos as our web filtering - and we feel like this is having some interference as the website looks fine from a home network. We have tried the following:

Whitelisting as many websites and domains that we have come across
Added them to a TLS exception list
Cleared cookies and cached data
Tried Incognito mode

Does anyone know how we can continue to try and fix this issue? This is one of the websites we have an issue with (https://portal.ncfe.org.uk/PRELOGIN/PreLoginPage.aspx). The first image is what it should look like and the second image is what it looks like for me.

User's image

Rukmini 30,865 Reputation points Microsoft External Staff Moderator

2026-02-26T12:07:54.2233333+00:00
Hello Sam,

Sophos HTTPS/TLS inspection interfering with Azure AD B2C page scripts is most likely the cause of this behavior.

Since the page functions properly when accessed outside of your network, network-level filtering that modifies or blocks necessary JavaScript/CSS files is the problem rather than the NCFE site.

The backdrop overlay does not render properly and prevents the login controls when those scripts fail to load (as seen in your screenshot).

Solution

Create a full SSL/TLS decryption exclusion rule in Sophos (not just a web whitelist) for the following domains:

portal.ncfe.org.uk

*.b2clogin.com

*.microsoftonline.com

*.azureedge.net

*.aadcdn.microsoftonline-p.com

Make sure There is no decryption nor inspection of traffic to these domains. Clear the browser cache and retry after applying the exclusion.

Let me know if any further queries - feel free to reach out!
Rukmini 30,865 Reputation points Microsoft External Staff Moderator

2026-02-27T03:28:49.1266667+00:00

Hello Sam, Following up to see if the above provided information was helpful. If you have any further queries do let us know.
Sam 1 Reputation point

2026-02-27T07:56:15.6+00:00

Hi Rukmini,

I haven't implemented this yet as a rule - but thank you for trying to provide a solution.

I will let you know if this has helped!

Thanks,

Sam
Rukmini 30,865 Reputation points Microsoft External Staff Moderator

2026-02-27T07:57:55.12+00:00

Hello Sam

Sure please keep me updated!

1 answer

Your answer

Rukmini 30,865 Reputation points Microsoft External Staff Moderator

2026-02-26T12:07:54.2233333+00:00

Hello Sam,

Sophos HTTPS/TLS inspection interfering with Azure AD B2C page scripts is most likely the cause of this behavior.

Since the page functions properly when accessed outside of your network, network-level filtering that modifies or blocks necessary JavaScript/CSS files is the problem rather than the NCFE site.

The backdrop overlay does not render properly and prevents the login controls when those scripts fail to load (as seen in your screenshot).

Solution

Create a full SSL/TLS decryption exclusion rule in Sophos (not just a web whitelist) for the following domains:

portal.ncfe.org.uk

*.b2clogin.com

*.microsoftonline.com

*.azureedge.net

*.aadcdn.microsoftonline-p.com

Make sure There is no decryption nor inspection of traffic to these domains. Clear the browser cache and retry after applying the exclusion.

Let me know if any further queries - feel free to reach out!
Rukmini 30,865 Reputation points Microsoft External Staff Moderator

2026-02-27T03:28:49.1266667+00:00

Hello Sam, Following up to see if the above provided information was helpful. If you have any further queries do let us know.
Sam 1 Reputation point

2026-02-27T07:56:15.6+00:00

Hi Rukmini,

I haven't implemented this yet as a rule - but thank you for trying to provide a solution.

I will let you know if this has helped!

Thanks,

Sam
Rukmini 30,865 Reputation points Microsoft External Staff Moderator

2026-02-27T07:57:55.12+00:00

Hello Sam

Sure please keep me updated!

Answer 1

Hello Sam,

Welcome to Microsoft Q&A,

Sophos community thread with the same type of issue (CSS formatting breaks when going through Sophos) and the recommended fix is to create an SSL/TLS inspection rule → “Don’t Decrypt” for the affected site(s).

This is the most common reason your B2C page looks like a “background overlay” is sitting on top of the sign-in panel: SSL inspection or content modification can break scripts/CSS or subresource integrity, which makes layout fallback go wrong.

https://community.sophos.com/sophos-xg-firewall/f/discussions/149307/css-formatting-issue-through-sophos

https://docs.sophos.com/nsg/sophos-utm/utm/9.7/help/en-us/Content/utm/utmAdminGuide/WebProtFilteringOptionsExceptions.htm

Please Upvote and accept the answer if it helps!!

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Issue loading B2CLogin pages correctly

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