Puppeteer: Multiple file uploads only work with <input type=file multiple>

Several files are uploaded to a file input without the multiple attribute.

Error message

Multiple file uploads only work with <input type=file multiple>

How this error happens

A native file input accepts multiple files only when it has the multiple attribute.

The snippets use an open Puppeteer page named page.

await page.setContent(
    '<input id="upload" type="file">'
);

const input = await page.$("#upload");

await input.uploadFile(
    "/absolute/path/first.csv",
    "/absolute/path/second.csv"
);

How to fix

Upload one file to a single-file input. If you own the form and it is meant to accept several files, give it the multiple attribute.

const input = await page.$("#upload");

await input.uploadFile(
    "/absolute/path/first.csv"
);

Things to keep in mind

The paths must refer to existing local files. Do not add multiple to a third-party form if the server only accepts one file.

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