Blocker
Noun · Slang & Abbreviations
Definitions
Blocker is a term in project management and software development describing any obstacle that prevents a team member from making progress on their work. In Agile methodologies (Scrum, Kanban), blockers are surfaced during daily standups, where each team member reports what they worked on yesterday, what they plan to do today, and what is blocking them. Common blockers include waiting for code review approval, dependencies on other teams, unclear requirements, access permissions not yet granted, infrastructure issues, and external API outages. In issue tracking systems, a blocking relationship links two tickets where one cannot proceed until the other is resolved. Resolving blockers quickly is one of the primary responsibilities of Scrum Masters and engineering managers. Persistent, unresolved blockers are a leading cause of missed sprint goals and developer frustration. The term is also used more casually to mean a significant obstacle (that meeting is a blocker for the rest of my day). Proactively identifying and escalating blockers is considered a key skill for effective team collaboration.
In plain English: Something preventing you from doing your work — usually waiting for someone else to finish something, make a decision, or give you access.
In bug tracking, a blocker is the highest severity level — an issue so critical it prevents a release, crashes the system, or causes data loss. Different from a 'dependency blocker,' which is a task that must complete before another can start.
Example: 'Mark it as a blocker — the payment API returns 500 errors for 30% of transactions. We cannot release until this is fixed.'
Source: bug severity level