Ran into an issue with the hugo site: GitHub Repo where the build GitHub action failed. And the errors is a new one for me that I’ve never seen.

My first thought was to rerun the failed action, but of course that didn’t work. So then it was time top read error, but I was rather lost.

Solution: GPT Instructor. The key is all in the prompt.

GPT Error Education

Prompt

Do you understand this error? If so can you teach me step by step how to read and understand the error myself and then provide the solution. Please respond as

```md <your answer> ``` , and where possible use cited sources and construct the answer as an article lesson.

Error

Run hugo
Start building sites … hugo v0.128.0-e6d2712ee062321dc2fc49e963597dd5a6157660+extended linux/amd64 BuildDate=2024-06-25T16:15:48Z VendorInfo=gohugoio

Total in 10 ms Error: error building site: process: readAndProcessContent: “/home/runner/work/pbrazeale.github.io/pbrazeale.github.io/content/posts/dev-week-062.md:5:9”: unmarshal failed: toml: incomplete number Error: Process completed with exit code 1.

Resulting Knowledge

Read the Error Like a Pro (and Fix It)

Error (from your CI log)

Run hugo
Start building sites …
hugo v0.128.0 …

Total in 10 ms
Error: error building site: process: readAndProcessContent: "/home/runner/work/pbrazeale.github.io/pbrazeale.github.io/content/posts/dev-week-062.md:5:9": unmarshal failed: toml: incomplete number
Error: Process completed with exit code 1.
1) How to read this kind of Hugo error

When Hugo fails on front matter it tells you:

  • Stage: process: readAndProcessContent → Hugo was parsing a content file’s front matter (the key–value block at the top of the Markdown). :contentReference[oaicite:0]{index=0}
  • File: content/posts/dev-week-062.md
  • Location: :5:9 → line 5, column 9 in that file.
  • Parser / format: unmarshal failed: toml: incomplete number → Hugo tried to decode TOML and tripped on a value it thought was a number, but that number was syntactically invalid TOML.

Recall: Hugo supports front matter in TOML (+++ … +++), YAML (--- … ---), or JSON ({ … }). Your file is using TOML. :contentReference[oaicite:1]{index=1}

2) What “TOML: incomplete number” usually means

TOML has strict rules for numbers. The most common ways to violate them:

  1. Leading zeros on integers

    • week = 062 ❌ → invalid; TOML integers cannot start with 0 (unless the value is exactly 0). Use 62, or if you need the padded form, make it a string: "062". :contentReference[oaicite:2]{index=2}

  2. Unquoted strings inside arrays, causing TOML to think you’re providing numbers or bare identifiers

    • tags = [2025, March 2025, Updates] ❌
      Hugo/TOML will try to parse 2025 as a number and then choke on March 2025. You want strings:
      tags = ["2025", "March 2025", "Updates"] ✅
      A nearly identical failure is shown in a recent forum thread. :contentReference[oaicite:3]{index=3}

  3. Malformed date/time offsets

    • Offsets must be zero-padded like +04:00, not +4:00. TOML datetimes follow RFC 3339 (and Hugo understands them in front matter). :contentReference[oaicite:4]{index=4}

  4. Numbers with stray characters, spaces, or bad separators

    • version = 1 . 2 ❌, build = 1_ ❌, etc. (underscores must be between digits). :contentReference[oaicite:5]{index=5}

  5. Wrong delimiter for the chosen front-matter format

    • If you use TOML keys but fence them with --- (YAML), the parser will misinterpret them and error. TOML must be fenced with +++. :contentReference[oaicite:6]{index=6}
3) Step-by-step: how you can debug these every time

  1. Jump straight to the file & position
    Open content/posts/dev-week-062.md and go to line 5, column 9.

  2. Confirm the front-matter fence
    Make sure it starts with +++ and ends with +++ (TOML). If it’s ---, either switch to YAML or change to +++. :contentReference[oaicite:7]{index=7}

  3. Scan keys on/near that line for “number-ish” values
    Look for:

    • Integers with leading zeros (007, 062, 01).
    • Unquoted items in arrays (tags = [2025, March]).
    • Datetimes with non-padded offsets (+4:00 instead of +04:00). :contentReference[oaicite:8]{index=8}

  4. Decide: number or string?

    • If it’s an identifier like a “week code” you display as 062, store it as a string: week = "062".
    • If it’s a tag, quote it: ["Dev Week", "2025", "Week 62"].
    • If it’s a real integer that must stay numeric, drop the leading zero: 62.

  5. Fix datetimes (if present)
    Use valid RFC 3339: date = 2025-09-20T07:00:00-05:00 (unquoted is fine in TOML). :contentReference[oaicite:9]{index=9}

  6. Rebuild locally with more detail
    Run hugo --verbose to get extra context in your terminal.

4) A likely fix for your post

Given the filename dev-week-062.md and the exact error at :5:9, two common culprits are:

  • A week = 062 style field, or
  • A tags = [2025, Week 62, …] array with unquoted items (or a date/time offset without zero-padding).

Here’s a safe TOML template you can paste over your front matter and then adjust values:

+++
title = "Dev Week 062"
# RFC 3339 datetime; America/Chicago on Sep 21, 2025 would be -05:00 if DST applies.
date = 2025-09-21T07:00:00-05:00
draft = false

# Keep numeric-looking labels as strings if you care about the leading zero.
week = "062"

# Always quote strings in arrays.
tags = ["Dev Week", "Logs", "2025", "Week 62"]
+++

Why these choices:

  • Leading-zero values as strings align with TOML’s “no leading zeros on integers” rule. Jamie Tanna | Software Engineer
  • Quoted tags avoid the “incomplete number” trap when the parser meets mixed types or spaces. The forum thread shows this exact failure mode. HUGO
  • RFC 3339 datetime is what TOML (and Hugo) expect. toml.io
5) Quick checklist for future posts
6) References & further reading
  • Hugo docs — Front matter (formats, types, and parsing). gohugo.io
  • TOML v1.0.0 — Numbers (no leading zeros) & Dates/Times (RFC 3339). Jamie Tanna | Software Engineer+1
  • Real-world failure: unquoted/numbery items causing toml: incomplete number. HUGO

TL;DR

Your build is failing because the TOML front matter in dev-week-062.md contains something that looks like a number but isn’t valid TOML (most often a leading-zero integer or an unquoted array item). Convert padded values to strings, quote your tags, fix any offset padding in dates, and rebuild.

Personal Takeaways

I could have solved this on my own had it not been first thing in the morning before my coffee. Two major clues. As GPT mentioned 5:9 tells me exactly the offending location. Also, if I’d just paid attention to my IDE it indicated that False was an improper format.

However, my point about GPT Education still stands, and I kept reading after solving the problem.

Major Hack

I’ve been using this line: where possible use cited sources and it’s been quite helpful, but ever since the GPT-5 drop, the quality of the cited sources and density has reached a college undergraduate paper level. Not just for technical documentation but also for personal research into other subjects. Truly brilliant.

I’m quite curious if the cited sources are built into the weights of the model, or if this is an emergent behavior of better agentic tool calling features. Has GPT mastered Googling?

Regardless. The next time your looking for detailed feedback from GPT, I high suggest you remix this prompt to your needs and see if you don’t prefer the outputs.

NOTE

I use the “wrap your answer in markdown” formatting request because all my notes end up in Obsidian and it makes my formatting job easier if it’s already pre laid out.