Skipped jobs in Azure DevOps pipeline

Situation

To explain my problem, I will use a very simple pipeline, containing a single stage with 4 jobs:

JobB depends on JobA, JobC depends on JobB, and JobD depends on JobC.

JobB has a condition that causes this job to be skipped.
JobC has a condition that it is never skipped.

JobD does not have any condition at all.

Below is the yml file I used for this:

pool:  vmImage: ubuntu-latestjobs:- job: JobA  steps:    - script: echo Job A- job: JobB  condition: false  dependsOn: JobA  steps:    - script: echo Job B- job: JobC  condition: true  dependsOn: JobB  steps:    - script: echo Job C- job: JobD  dependsOn: JobC  steps:    - script: echo Job D

Results

My expectation of this pipeline was that jobs A, C, and D would run, because jobD does not have a condition at all.

The actual result is shown in the picture: jobD is skipped. But why?

The reason appears to be that a job without a condition will have an implicit condition succeeded(). This condition means: all previous jobs must succeed. For some reason a job that is skipped is not successful. This means that JobD fails, because one of the upstream jobs is skipped.

How to fix this

The fix for this problem is relatively easy: add an explicit condition to JobD. For example, check that JobC is successful:

condition: succeeded('JobC')

Conclusion

If you expect that a job might be skipped in a dependency tree, always add an explicit condition to downstream jobs.