HTML instead of JSON (starts with <) Playbook

HTML instead of JSON (starts with <). Step-by-step no-upload workflow: validate, locate root cause, fix quickly, and verify.

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TL;DR: Validate -> locate exact failing spot -> fix the minimal part -> re-validate.

Execution steps

  1. Validate input locally. Start with a validator or parser-friendly converter.
  2. Locate root cause. Use line/position/error token to isolate one failing place.
  3. Apply a minimal fix. Do not refactor all content at once.
  4. Re-validate and continue. Once clean, convert/export safely.

Recommended tools

Relevant guides

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Unexpected character encountered while parsing value: &lt;. Path '', line 0, position 0.: how to fix it (Newtonsoft.Json)

Newtonsoft.Json error (&lt;. , line 0, position 0.): common causes (HTML instead of JSON, extra chars) and a safe no-upload validation workflow.

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After parsing a value an unexpected character was encountered: }. Path '', line 1, position 2.: how to fix it (Newtonsoft.Json)

Newtonsoft.Json error (}. , line 1, position 2.): common causes (HTML instead of JSON, extra chars) and a safe no-upload validation workflow.

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Unexpected character ('&lt;' (code 60)): expected a valid value (JSON String, Number, Array, Object or token 'null', 'true' or 'false'): how to fix it (Jackson)

Jackson JSON error (expected a valid value (JSON String, Number, Array, Objec...): why it happens (HTML/text instead of JSON, truncation) and the fastest fixes (no upload).

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System.Text.Json.JsonException: 'o' is an invalid start of a value. LineNumber: 0 | BytePositionInLine: 0.: what it means and how to fix it

Newtonsoft.Json error (&#039;o&#039; is an invalid start of a value. LineNumber: 0 | ByteP...): common causes (HTML instead of JSON, extra chars) and a safe no-upload validation workflow.

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System.Text.Json.JsonException: 'u' is an invalid start of a value. LineNumber: 0 | BytePositionInLine: 0.: what it means and how to fix it

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System.Text.Json.JsonException: '&lt;' is an invalid start of a value. LineNumber: 0 | BytePositionInLine: 0.: what it means and how to fix it

Newtonsoft.Json error (&#039;&lt;&#039; is an invalid start of a value. LineNumber: 0 | ByteP...): common causes (HTML instead of JSON, extra chars) and a safe no-upload validation workflow.

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System.Text.Json.JsonException: 'N' is an invalid start of a value. LineNumber: 0 | BytePositionInLine: 0.: what it means and how to fix it

Newtonsoft.Json error (&#039;N&#039; is an invalid start of a value. LineNumber: 0 | ByteP...): common causes (HTML instead of JSON, extra chars) and a safe no-upload validation workflow.

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Related actions

Related playbooks

Related by intent

Expert signal

Expert note: HTML instead of JSON (starts with <) usually resolves fastest when triage starts from strict validation and then branches to comparison/alternative paths based on input quality.

Data snapshot 2026

MetricValue
Intent confidence score79/100
Predicted CTR uplift potential25%
Target crawl depth< 4 clicks

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