GitHub · Pull requests · REST API · Checked October 25, 2026

GitHub: the diff of a pull request answered 406, or files are missing

GitHub's REST API gives a pull request's changes in two ways: the whole diff, when the pull request (GET /repos/OWNER/REPO/pulls/NUMBER) is asked for with the media type application/vnd.github.diff, and the list of changed files (GET /repos/OWNER/REPO/pulls/NUMBER/files), with each file's patch. Both stop at a number of files. The answers below are what api.github.com said on October 25, 2026 for a public pull request with 1,545 changed files, with the rules from GitHub's documentation behind them.

HTTP/1.1 406 Not Acceptable

{"message":"Sorry, the diff exceeded the maximum number of files (300). Consider using 'List pull requests files' API or locally cloning the repository instead.",
 "errors":[{"resource":"PullRequest","field":"diff","code":"too_large"}]}

406 "too_large": the diff has more than 300 files

The diff comes in one answer, and GitHub does not make it for a pull request that changes more than 300 files: it answers 406 Not Acceptable, with the code too_large on the field diff, and points to the list of files. The same pull request as JSON (application/vnd.github+json) answered 200; only the diff was refused.

The list of files stops at 3,000

At most 3,000 files: GitHub's documentation says the list includes a maximum of 3,000 files, 30 a page by default and up to 100 with per_page. The Link header's rel="last" names the last page; a page after it answered 200 with an empty list.
To tell whether files are missing, compare the number of files you received with changed_files in the pull request itself (GET /repos/OWNER/REPO/pulls/NUMBER): for the pull request above it was 1545, all of them in 16 pages of 100.
404 Not Found: no pull request has that number, or your token cannot see the repository: GitHub answers 404, not 403, for a private repository you cannot access (see which permission to add). The documentation also lists 422 (validation failed, or the endpoint has been spammed), 500 and 503 for this list.

What to do

406: read the list of files instead, or compare the branches yourself: git fetch origin pull/NUMBER/head gets the pull request's head (GitHub keeps it under that ref), and git diff origin/BASE...FETCH_HEAD shows every file, as GitHub's Files changed does.
More than 3,000 files: the API does not give the rest; use the same git diff.
On the web: the Files changed tab has its own limits on lines, size and files, and hides generated files by default (see file diff not shown).

In IntelliJ IDEA: the changes come from the list of files, never from the diff

How the GitHub support built into IntelliJ IDEA reads a pull request's changes, in its source (checked October 31, 2026; IntelliJ IDEA: GHPRChangesServiceImpl.kt, GHPRChangesDataProviderImpl.kt, GithubApiRequests.kt, GithubApiPagesLoader.kt):

It never asks for a pull request as a diff. Its only request with the diff media type compares two commits, so the 406 too_large above does not come from the IDE.
The whole pull request's changes come from the list of files above, asked for without per_page, so 30 a page by GitHub's default, and followed through GitHub's next links until there are none. So it has at most the 3,000 files the list gives.
Each commit's changes come from the commit itself (GET /repos/OWNER/REPO/commits/SHA), up to 50 commits at a time, also followed through the next links. The merge base comes from comparing the pull request's base and head commits (GET /repos/OWNER/REPO/compare/BASE...HEAD).

GitHub pull requests in IntelliJ IDEA

Pull Request Inbox for GitHub, a plugin by Lesstep for JetBrains IDEs 2024.1 or later, reads a pull request's changes from the list of files, 100 a page, up to the 3,000 files GitHub gives, so the diff's limit of 300 files does not apply to it. Each file opens in the IDE's diff, from the merge base of the target branch to the head commit, as GitHub's Files changed shows it. For a pull request with more than 3,000 changed files, the Files tab says only the first ones are listed, and git diff shows the rest. The review inbox, diffs and conversations are free; approving, commenting and merging are Pro (US$1.50 a month, with a 30-day trial).

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