GitHub · Pull requests · Diffs · Checked October 27, 2026

GitHub: a file diff is not shown in a pull request

GitHub limits the diffs it shows for commits, pull requests and compare views. Some portions of a limited diff may be displayed, but anything exceeding the limit is not shown (GitHub's diff limits, checked October 27, 2026). Files marked as generated are also hidden by default in diffs.

The diff limits

One file: 400 lines and 20 KB of a file diff are loaded automatically. No single file diff may exceed 20,000 lines that you can load, or 500 KB of raw diff data.
The whole pull request: no total diff may exceed 20,000 lines that you can load, or 1 MB of raw diff data.
Files: a single diff holds at most 300 files, and at most 25 renderable files, such as images, PDFs and GeoJSON files (for the image and document views, see an image or document diff not shown).
Not the API: the REST API has its own limits, 300 files for the whole diff and 3,000 for the list of files (see diff too large (406)).

Other reasons a diff is hidden

Generated files: a file marked with the linguist-generated attribute in .gitattributes is hidden by default in diffs and left out of the repository language statistics (GitHub's customizing how changed files appear).
Whitespace: the Files changed tab can hide whitespace differences. The choice applies only to that pull request, and is remembered the next time you visit it (GitHub's starting a review).
The file filter: the files can be filtered to show only the ones you want to review, so a filter can leave a file out of the tab.
Viewed: a file marked as viewed collapses, and is unmarked when it changes again (see viewed mark cleared).

What to do

A long file: load the rest of its diff on the page, up to 20,000 lines or 500 KB.
Past the limits: GitHub does not show it; compare the branches with git diff in a clone, as described in diff too large (406).
A file that should not count as generated: unmark it in .gitattributes, for example bootstrap.min.css -linguist-generated; to mark one, use search/index.json linguist-generated. The file uses the same matching rules as .gitignore.
Whitespace and filters: check the diff settings and the file filter of the Files changed tab. When a file shows every line changed instead, see line endings.

In IntelliJ IDEA: the file list comes from GitHub, the diff from the fetched commits

How the GitHub support built into IntelliJ IDEA lists and shows the changed files of a pull request, in its source (checked October 31, 2026; IntelliJ IDEA: GHPRChangesServiceImpl.kt, GHPRChangesDataProviderImpl.kt, GithubApiRequests.kt, GitBranchComparisonResult.kt, GitBranchComparisonResultImpl.kt):

The file list: the files are GitHub's REST list of the pull request's files (GET /repos/OWNER/REPO/pulls/NUMBER/files), read until there is no next page, so the limit GitHub puts on that list (3,000 files, above) still applies. Each commit's own files come from GET /repos/OWNER/REPO/commits/SHA.
The diff: before showing diffs, it fetches the base commit and refs/pull/NUMBER/head into the local repository when they are not there. Each file's diff compares the whole file at the merge base (found with GitHub's compare) with the whole file at the head commit, both read from git, not the part GitHub shows on the page.
A file without patch text: a file that GitHub's list sends without its patch is kept as a binary change, still listed and compared from git the same way.

GitHub pull requests in IntelliJ IDEA

Pull Request Inbox for GitHub, a plugin by Lesstep for JetBrains IDEs 2024.1 or later, lists the changed files GitHub gives, up to 3,000, and opens each one in the IDE diff by reading the whole file at the merge base of the target branch and at the head commit, next to the pull request's reviews, checks and conversations. It does not read .gitattributes, so a file marked as generated is listed and opened like any other. The review inbox, diffs and conversations are free; approving, commenting, resolving and merging are Pro (US$1.50 a month, with a 30-day trial).

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