Conflicting Allow/Disallow rules
When Allow and Disallow overlap, Google resolves the conflict by the most specific rule, not by order. If I am not thinking in those terms, the file does something different from what I intended.
Overlapping rules give ambiguous instructions.
Why it matters
Mis-scoped rules can block intended pages or expose intended blocks; Google resolves by most-specific/longest-match, which may not be what you intended.
How to fix it
Audit rule precedence; test in Search Console’s robots.txt tester.
How to find it on your site
- List overlapping Allow and Disallow rules that touch the same paths.
- Remember Google uses the longest matching rule, and Allow wins exact ties.
- Test the exact URLs in the Search Console robots.txt tester to see the verdict.
- Rewrite the rules so the intended behaviour does not depend on subtle precedence.
Cross-reference to ranking and citation factors
Ambiguous rules usually surface as crawl coverage surprises rather than ranking changes, but they can leave important URLs unintentionally blocked.
Impact
Medium. Risk of unintended crawl gaps. Direct (documented precedence).
Evidence
Google applies the most specific (longest) matching rule. Google Search Central, Intro to robots.txt