I created a new A/B test and added modification code (Mbox code) under Experience A using the Custom Code option. The changes saved successfully in the VEC editor.However, during validation:Experience A delivers nothing (and appears empty in the VEC editor).Experience B, where I did not add any code, is unexpectedly delivering the Mbox code. The Mbox code is appended on Experience B, and when I open the VEC it shows up there.Has anyone faced this issue before? How can I resolve it so that the custom code applies only to Experience A?

Question

Issue with A/B Test – Custom Code not delivering on Experience A

Forum|Forum|4 months ago
September 23, 2025
3 replies
823 views

I created a new A/B test and added modification code (Mbox code) under Experience A using the Custom Code option. The changes saved successfully in the VEC editor.

However, during validation:

Experience A delivers nothing (and appears empty in the VEC editor).
Experience B, where I did not add any code, is unexpectedly delivering the Mbox code. The Mbox code is appended on Experience B, and when I open the VEC it shows up there.

Has anyone faced this issue before? How can I resolve it so that the custom code applies only to Experience A?

Target

RaghavAggarwal

Level 2

It might be due to new UI the code is not appended on the specific experience. Click on the specific exp in which you have to append the code and further check the preview in the activity through browse or design option.

bkmills

Level 2

I did this when I experienced this issue this morning. After carefully selecting the correct experience and visually confirming that is was correct, the above still occurred. I think this is a bug that was introduced yesterday!

Gokul_Agiwal

Community Advisor

Hi @saravanan_digital_analytib

I believe the Experience A is the control version and Experience B is your personalized version is this correct?

To add specific custom code to specific experience you can chose the right experience from the left panel, and then click on Add modification - like below

Once you chose the right experience - you can add modification type as custom code - which will save in the same experience you chosen.

can you check are you following the these steps? In case if issues still there please post it so we can check

Thanks

bkmills

Level 2

@gokul_agiwal @saravanan_digital_analytib - I started experiencing the same exact thing today. I added code to the control but target switched it to the challenger. I did the inverse and the same thing happened. This never happened before the release yesterday.

P

preeyavs28

@gokul_agiwal - We recently started facing the same issue of "applying initial load" getting stuck in infinite loop and custom experiences' aren't retained in A/B module.

Gokul_Agiwal

Community Advisor

Hi @preeyavs28 @bkmills @saravanan_digital_analytib @raghavaggarwal

Based on the comments from you, I just give a try in my organization sandbox, apply the initial modification as custom code for Experience A and later save and close it. The custom code remain in the experience A. I did inverse and the code remain in the specific experience where I added.

Also performed the same changes in my client sandbox and it's working as expected.

Just checked the release notes - the latest updates rolled out on 22nd September 2025.

Target Standard/Premium 25.9.2 (September 22, 2025) https://experienceleague.adobe.com/en/docs/target/using/release-notes/release-notes

I would suggest clear cache, cookies and then give a try again. If you're still facing issues then raise a support ticket with right priority so that support team address the issues asap.

Hope this helps!

Thanks,

Gokul

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