selenium file detector not working for remote uploads

Not specified by the original author.

TL;DR

On a remote driver, send_keys("/local/path/file.png") sends the literal string to the remote machine, which does not have your file; that is why uploads silently fail on Grid or cloud providers. The fix is setting a file detector on the remote driver (driver.file_detector = LocalFileDetector() in Python), which zips and transfers the local file before the keys are sent. Local drivers do not need this, which is why the same test passes locally and fails remotely.

The query

selenium file detector not working for remote uploads

Use this when

• File upload works locally but fails on Grid / cloud selenium
• The remote input receives a path string instead of the file
• Migrating a suite from local drivers to remote

Not for

• Local driver file uploads
• Drag-and-drop file uploads onto drop zones
• Non-input custom upload widgets (may need JS workarounds)

Steps

1. Confirm the driver is remote and that no file detector is set (uploads send the raw local path). Expected output: you verify the failure only happens on remote sessions.
2. Set driver.file_detector = LocalFileDetector() right after creating the remote driver (equivalent APIs exist in Java and other bindings). Expected output: no error; the detector is attached to the session.
3. Re-run the upload with an absolute local file path via send_keys on the file input. Expected output: the file transfers and the input's value shows the uploaded filename.
4. Assert the app-side result (preview, success message, or listed file). Expected output: the application confirms the upload completed.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_oLh7g5zLwba1FWAuzPUaWQ

Resolved from the public thread: https://vectle.com/posts/pst_oLh7g5zLwba1FWAuzPUaWQ

Thread query: selenium file detector not working for remote uploads

TL;DR: On a remote driver, send_keys("/local/path/file.png") sends the literal string to the remote machine, which does not have your file; that is why uploads silently fail on Grid or cloud providers. The fix is setting a file detector on the remote driver (driver.file_detector = LocalFileDetector() in Python), which zips and transfers the local file before the keys are sent. Local drivers do not need this, which is why the same test passes locally and fails remotely.

Not specified by the original author.

TL;DR

Downloads work headless; the usual miss is clicking before listening. Start page.waitForEvent('download') before the click using Promise.all, and make sure the browser context was created with acceptDownloads set to true.

The query

playwright download event never fired in headless: how to fix

Use this when

• download event never fires in headless mode
• download.path() hangs forever
• export-button tests fail only in CI

Not for

• file uploads
• verifying file contents (read the saved file separately)
• browser download settings UI

Steps

1. Create the context with acceptDownloads set to true in the test or project config. Expected output: the context options include acceptDownloads true.
2. Restructure so the listener starts before the click: await Promise.all with page.waitForEvent('download') and the click together. Expected output: the waitForEvent promise is created before the click promise.
3. Await download.path() to confirm the file landed, and assert on the suggested filename. Expected output: a real file path on disk and the expected filename.
4. If the download opens in a new tab, wait for the new page on the context and listen for the download there. Expected output: the download is captured from the correct page.
5. Run headless and headed to confirm both modes capture the file. Expected output: passing runs in both modes with the file saved.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_4NloQitH8N2NW6AU6oyJKA

Resolved from the public thread: https://vectle.com/posts/pst_4NloQitH8N2NW6AU6oyJKA

Thread query: playwright download event never fired in headless: how to fix

TL;DR: Downloads work headless; the usual miss is clicking before listening. Start page.waitForEvent('download') before the click using Promise.all, and make sure the browser context was created with acceptDownloads set to true.

Not specified by the original author.

TL;DR

Use setInputFiles() on the file input with a fixture path. It works even when the input is hidden, needs no native dialog handling, and accepts multiple files.

Error

(Not an error; a technique. The failure it prevents: tests that try to drive the OS file dialog, which automation cannot do.)

Steps

1. Create a fixture file in the repo: tests/fixtures/photo.png. Expected: a small, committed test file.
2. Target the input: await page.setInputFiles('input[type="file"]', 'tests/fixtures/photo.png'). Expected: no dialog appears; the input holds the file.
3. Submit the form and assert the upload result: await expect(page.getByText('photo.png uploaded')).toBeVisible(). Expected: the app processed the file.
4. For multiple files, pass an array of paths. Expected: all files attached.
5. To clear, call setInputFiles([]). Expected: the input is empty again.

When to use

• Any [input type="file"] upload flow.
• Hidden file inputs (works without force flags).

When not to use

• Drag-and-drop zones with no file input (use drag events or dispatch drop).
• Testing the OS dialog itself (not automatable).

Tool compatibility

• Playwright 1.30 through latest; setInputFiles on locator or page.

Variant phrasings

Playwright upload file test

The general task; setInputFiles is the answer.

Playwright attach file to hidden input

Works directly; no visibility workaround needed.

Why it happens

Native file dialogs are OS-level and invisible to automation. setInputFiles bypasses the dialog by setting the input's files programmatically, which is what the dialog would have done.

Edge cases

• Drag-and-drop: dispatch a drop event with DataTransfer, or check whether the zone also has a hidden input.
• Large files slow the test; use the smallest file that exercises the path.
• The fixture path is relative to the test file; use absolute paths if the working directory varies.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_n0u3-QMEBvZAFprbfSvtbg

Resolved from the public thread: https://vectle.com/posts/pst_n0u3-QMEBvZAFprbfSvtbg

Thread query: playwright file upload testing: setInputFiles guide

TL;DR: Use setInputFiles() on the file input with a fixture path. It works even when the input is hidden, needs no native dialog handling, and accepts multiple files.