Half of all 'TFTP not working' complaints are really root-folder mistakes: the file is somewhere else, the name is typed differently, or the folder is a junk drawer of old configs. Set the folder up properly once and both problems disappear.
A TFTP server has no browsing, no search and no subfolder logic worth relying on. A device asks for a file name, and the server looks in exactly one place: the root folder (also called the base directory). If the file is not there, or its name does not match character for character, the transfer fails — the protocol has no way to say 'did you mean?'. That simplicity is a gift if you respect it: one short folder, today's files only, names written down before you start.
Create the folder at the root of a drive, for example C:\TFTP-Root. Short paths survive every tool's settings screen, are easy to read over the phone to a colleague, and never fall foul of old software that handles long paths or spaces badly. Then set this exact folder as the root / base directory inside your TFTP tool and restart the server so the setting truly applies.
Downloading a firmware file to your Downloads folder and pointing the device at its name will fail every time. Before any transfer, open the root folder and look at the file sitting there. For uploads (device sending to you), the opposite applies: the folder must be writable, and some older servers additionally require an empty file with the target name to already exist — creating a blank file with the exact name first is a harmless trick that fixes that class of refusal.
TFTP file names are literal. Config.cfg, config.cfg and config.cfg (with a trailing space) are three different requests. Before starting, write down the exact file name from the folder — including extension and capitalisation — and type that into the device command. In the folder, use names that explain themselves: device, purpose and date, like switch-core-config-2026-10-25.cfg. You will thank yourself the day you must restore one.
Because TFTP has no login, everything in the root folder is effectively public to the LAN while the server runs. Keep the folder to the files for the current job. When a backup completes, move it the same day into your real backup system — a dated folder on the file server or backup drive, under whatever access control that system has. The root folder returns to empty, ready for the next job and holding nothing worth stealing in between.
Resist creating TFTP2, New folder (3) and a different root inside every tool you try. One known folder means you always know where a device will look, where uploads landed, and what to check when a transfer fails. If you test a second TFTP tool, point it at the same folder. Consistency is what turns a five-minute job into a one-minute job.
Uploads fail silently when the server process cannot write to the folder — for example when the tool runs as a service under a limited account and the folder sits inside another user's profile. A folder at the drive root, with normal modify rights for the account running the tool, avoids the whole class of problem. If downloads work but uploads refuse, suspect folder write permission before anything exotic.
The full TFTP server setup — installation, root folder, firewall and a live transfer — is shown step by step in the video.
▶️ Watch Full VideoAlmost always one of three folder facts: the file is not actually inside the folder set as the server's root (Downloads is the usual suspect), the name typed on the device differs from the real name by a letter, case or extension, or the tool was not restarted after you changed its root folder setting. Check those three before touching anything else.
Behaviour varies by tool and device, and the base protocol has no folder concept at all — some setups accept a path in the request, many refuse it. The reliable practice is flat: every transfer file directly in the root folder, moved into organised storage afterwards. One flat folder removes an entire category of failures.
In your normal backup system — a dated, access-controlled location such as the office file server or backup drive — not in the TFTP root. The root is a transfer workbench that is briefly open to the whole LAN by design. Finished backups deserve the same protection as any other sensitive file, because configurations contain password hashes and network details.