- Did something actually break?
- Is it perspective/perception thing instead of a solid problem?
- Is it that you don’t have data/values or they aren’t being connected?
- What does tail’ing the test/development log files show?
- State changes
- Does a reload / restart of server / using other device fix it
- Where is the break at based on what is affected?
- Can you output flags or sentences to help identify where firing?
- How many things affected?
- How deeply or totally were things affected?
- What was your last change?
- What was your last commit to that branch?
- Similarities / Shared in the systems / characteristics of the affected systems / components
- Can you comment stuff out until it works?
- Does changing test coverage or stubbing work?
- Does using the code in isolation work?