HTML instead of JSON (starts with <): validate-first workflow vs repair-first workflow

A practical migration for HTML instead of JSON (starts with <): trade-offs between validate-first workflow and repair-first workflow, plus actionable next steps.

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TL;DR: Start strict on a sample, apply minimal fixes, then scale only after validation passes.

Decision matrix

Criteria validate-first workflow repair-first workflow
Best when You need strict, repeatable output You need rapid triage on messy input
Risk profile Lower hidden-issue risk, more upfront checks Higher hidden-issue risk, faster initial pass
Typical speed Slower first pass, faster downstream debugging Faster first pass, may need rework later
Good for Stable JSON pipelines One-off fixes and incoming unknown formats
Avoid if Input is heavily malformed and urgent turnaround is required You need audit-grade guarantees

Choose validate-first workflow when

  • You need deterministic results for repeated JSON runs.
  • You are fixing production data where hidden breakage is costly.
  • You want clear pass/fail criteria before conversion or export.

Choose repair-first workflow when

  • You are in early triage and need to narrow the problem quickly.
  • You are dealing with mixed-quality inbound files from multiple sources.
  • You need an iterative cleanup loop before strict validation.

Recommended no-upload workflow

  1. Validate a representative sample first. Confirm exact error class/position.
  2. Pick workflow A or B. Use strict path for quality, flexible path for triage.
  3. Apply the smallest safe fix. Avoid broad rewrites before validation is green.
  4. Re-validate and convert/export. Only then run batch processing.

Recommended tools

Relevant guides

Auto-selected from existing guides for this topic. Need more: search by keyword.

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

Newtonsoft.Json error (&#039;u&#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.

Read guide

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.

Read guide

Invalid JSON primitive: ...: how to fix it (Newtonsoft.Json)

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

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Related actions

Related migrations

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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