Troubleshooting: Why Did Claude Do That?
Most "Claude is being weird" moments have a simple cause. Here are the common ones and the fix.
"It made up a fact / fake source"
Why: the model generated a plausible-but-false continuation (hallucination). Fix: give it the source text and say "answer only from this; if it's not here, say so." Verify anything that matters.
"It forgot what I said earlier"
Why: the conversation outgrew the context window, so older text dropped off — or it's a new session (no memory by default). Fix: restate the key info, or start a fresh chat for a new topic.
"It ignored my instruction"
Why: the instruction was buried in a long prompt, ambiguous, or contradicted by something else. Fix: put the instruction up top and restate it at the end; be specific; remove conflicting asks. See Prompting Basics.
"It refused something reasonable"
Why: the request pattern-matched to something sensitive, or context was missing. Fix: add legitimate context and be specific about your goal. If you're building on the API, handle refusals gracefully — see Refusals & Safety.
"The output is generic / bland"
Why: not enough constraints or no example of what "good" looks like. Fix: give it a role, a sample of the voice you want, and a tight format.
"The answer was wrong on numbers/math"
Why: LLMs reason about math but aren't exact calculators. Fix: ask it to show steps, or give it a tool/code to compute.
"It won't stop being verbose / too brief"
Fix: say exactly what you want — "answer in 3 bullets, no preamble" or "give me the full reasoning." In Claude Code, consider Output Styles.
"Claude Code did something I didn't expect to my files"
Why: broad permissions let it act without asking. Fix: use Plan Mode for big changes and tighten your allow/deny rules.
:::tip The universal first move Before assuming it's broken, re-read your prompt as if you were a literal stranger. Nine times out of ten the fix is more context or a clearer ask. :::
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