What does ERR_FILE_NOT_FOUND mean?

Chrome was asked to open a file:/// path and nothing exists at that exact path. It is the local-disk version of a 404: the file was moved, renamed or deleted, or the path Chrome was given is not the path you think it is.

Why does the first page open but every link inside it fails?

Only the entry file is where Chrome expects. The pages it links to were left behind — not copied, not attached, or still inside a zip. The links are relative to the page's folder, so they need the same folder structure next to it.

Why do links fail when I open a report from inside a zip on Windows?

Double-clicking an HTML file inside a zip in File Explorer extracts that one file to a temporary folder and opens it from there. Its sibling pages, scripts and images are still inside the zip, so every relative link from the temporary copy points at nothing. Extract the whole zip first, then open the file from the extracted folder.

Can a # or ? in the file name cause ERR_FILE_NOT_FOUND?

Yes. In a URL, # starts a fragment and ? starts a query, so a link to report#2.html asks Chrome for a file called report. Rename the file, or percent-encode the character in the link (report%232.html).

How do I share a multi-page HTML report so links work for everyone?

Either send the whole folder as a zip and ask people to extract it before opening, or publish the folder to a host so every page has a real URL. Comma accepts a folder or zip upload and gives one link where relative links between pages work and readers can comment.

ERR_FILE_NOT_FOUND

You double-click an HTML file, or click a link inside one, and Chrome shows a grey page:

Your file couldn't be accessed
It may have been moved, edited, or deleted.
ERR_FILE_NOT_FOUND

The address bar holds the answer. It starts with file:///, and it is the exact path Chrome looked for. Compare it with where the file really is — the difference is the bug.

The five usual causes

What you did	What actually happened
Reopened a bookmark, a history entry or a tab	The file was moved, renamed, or was a temporary copy that got cleaned up
Opened a report straight from inside a zip	Only that one file was extracted; its siblings stayed in the zip
Opened `index.html`, clicked through to a page	The linked page was never copied, attached or uploaded with it
Clicked a link to `run#3.html` or `what?.html`	`#` and `?` end the path in a URL, so Chrome asked for a different file
Opened an attachment from Outlook or a chat app	It ran from the app's temp folder, which is emptied later

Moved, renamed or temporary

A bookmark to a file:/// path is a pointer to one spot on one disk. Move the folder, rename it, sync it to another machine, or open it from the Downloads folder after a cleanup, and the pointer is dead. Mail clients are the worst case: Outlook opens an HTML attachment from a hidden temp folder, so reloading that tab a day later fails even though the email is still in your inbox.

Fix: save the file somewhere permanent first, then open it from there.

Opened from inside a zip

On Windows, File Explorer shows a zip like a folder. Double-clicking an HTML file in it extracts only that file to a temporary folder and opens it. The page renders, maybe without its styles — but every link to another page, and every image, points at a folder that doesn't exist. CI artifacts (GitHub Actions, GitLab, Jenkins) always arrive this way, which is why coverage and test reports are the most common victims.

Fix: right-click the zip → Extract All, then open the HTML from the extracted folder.

The linked page was never sent

A multi-page report — a coverage report, a Sphinx or MkDocs site, a JaCoCo or Allure output, an Excel workbook saved as a web page — is a folder, not a file. Send only index.html and the first page opens fine on the other side. Every click after that is ERR_FILE_NOT_FOUND, because the links are relative (src/app.html) and src/ is on your machine.

Fix: send the whole folder as a zip, or publish it so each page has a real URL. If the report is really one page with images and CSS, collapse it into one self-contained file with the HTML inliner and there are no siblings to lose.

`#`, `?` or `%` in a file name

File names may contain characters that mean something in a URL. A link href="results#2.html" is read as the file results plus a fragment 2.html. Same for ? (query string) and a bare % (start of an escape). The file exists; Chrome is asking for a different one.

Fix: rename the files to letters, digits, - and _, or encode the character in the link — results%232.html. Spaces are fine in practice, but %20 is the safe form if a generator writes the links.

A path that only exists on your machine

If the address bar shows file:///C:/Users/someone-else/… or /home/runner/work/…, the link was written as an absolute path by whatever generated the report. It worked on the machine that built it.

Fix: make the generator write relative links (os.path.relpath in Python, path.relative in Node). If the page is being served over http(s) instead, Chrome blocks the same link with a different message — see “Not allowed to load local resource”.

The way out of file:// for good

Every cause above is the same underlying problem: a file:/// path is only valid on one disk, in one folder layout, at one moment. The fix that stops all five is to give the report a real URL.

Comma takes a single HTML file, a folder, or a zip (multi-page reports keep their relative links between pages), and returns one link that opens the same for everyone — no extracting, no temp folders. Readers can open it without an account and pin comments on the exact line or chart they mean; commenting needs a free sign-in.

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