Incident Report: Recipe with a signing error in Prod on 02/14/2020

[SoftVision-CiprianMuresan]

[Affected Versions]:

• Firefox Nightly 75.0a1, Build ID 20200214100511
• Firefox Beta 74.0b3, Build ID 20200214015126

[Affected Platforms]:

• Windows 10 x64

[Prerequisites]:

• Have access to the Delivery Console.

[Steps to reproduce]:

1. Create a new multi-preference experiment recipe and fill it with valid data (make sure you select a couple of filters and additional filters).
2. Save and request approval for the newly created recipe.
3. Make changes to the recipe (slug and title) without waiting for approval.
4. Request approval again and receive approval.
5. Publish the recipe and disable it after a few minutes.
6. Change the recipe (remove and add a regular filter and additional filter).
7. Request approval and receive approval.

[Expected result]:

• No signing errors appear.

[Actual result]:

• The recipe generated a signing error.

[Notes]:

• In the second round of changes I removed one of the regular filters (channel) and added a different one (locale), removed an additional filter ('keyword'|preferenceExist) and added an additional filter (normandy.channel == '<value>').
• The multipref recipe I made had 2 branches (control and variant) and 1 pref that needed to be changed (trailhead.firstrun.branches).