# Fix failed file transfers

## How file transfer works

- **To the customer:** click **Send file** in the viewer toolbar, or drop files onto the remote screen. Files arrive in the customer's **Downloads** folder, in a **Blink** subfolder. Blink checks every file after it arrives and only keeps it if it is complete and unchanged.
- **From the customer (Windows):** the customer clicks **Send file** on the Blink banner, or **Send file to technician...** in the Blink tray icon menu. The file goes to the technician who used the session most recently. It appears in the viewer's transfer list as **received · accept to save**, and is only saved to your computer when you click **Accept**.

The transfer list in the viewer shows each file's progress and, when one fails, the reason.

## The Send file button is missing

1. Your role does not include file transfer for this session. Ask an administrator to check your role in **Roles**.
2. If the viewer shows **Is this your customer's computer?**, nothing reaches the computer until you confirm it. Check the computer name and signed-in user with the customer, then click **Confirm and take control**.

## Files to the customer fail

Common reasons in the transfer list:

| Reason | What to do |
|---|---|
| **the customer is not connected** | Wait until the session is connected again, then send the file again. |
| **too many transfers** | Wait for the current transfers to finish. |
| **no answer from the server** or **no answer from the customer** | The connection dropped. Send the file again once the session is back. |
| **stopped by customer** or **cancelled by customer** | The customer stopped it. Check with them. |
| **sha256 mismatch** or **verification failed** | The file did not arrive intact and was not kept. Send it again. |

Also check:

1. The customer has enough free disk space for the file.
2. On a Mac, the first file may make macOS ask whether Blink can use the Downloads folder. The customer must allow it.
3. In an Access session, someone must be signed in to Windows: files go to the signed-in user's Downloads folder. With nobody signed in, the transfer is refused.

## Files from the customer fail

| Reason | What to do |
|---|---|
| **no technician can receive files** | No technician in the session has file transfer allowed, or nobody has the viewer open. Open the viewer, then ask the customer to send again. |
| **only 4 files at a time; accept or decline the others first** | Click **Accept** or **Decline** on the files already waiting. |
| **not enough room in the browser; accept or decline the other files first** | Same as above. Files waiting for **Accept** are held in your browser, up to 1 GiB in total. |
| **file too large for the browser (max 1 GiB)** | Files over 1 GiB cannot be received in the viewer. Ask the customer to split or compress the file, or share it another way. |
| **the transfer stalled** | Nothing arrived for a minute. Ask the customer to send it again. |

Files that can run programs (such as `.exe`, `.msi`, `.ps1` or macro-enabled Office files) show a warning and a **Save anyway** button instead of **Accept**. Only save them if you expect the file.

Customers can send files to you from Windows computers. The Mac support tool does not have a **Send file** option.

## When to contact IZT

Contact [IZT](https://izt.app) if transfers fail with the same reason on a stable connection, or with a reason not listed here. Send the session id, the file size, the reason shown, and the session log. See [Collect logs for IZT support](/troubleshooting/collect-logs/).