kovidgoyal/kitty · error

Could not detect the MIME type for: %s use --mime to specify

Error message

Could not detect the MIME type for: %s use --mime to specify it manually

What it means

In run_get_loop, when no --mime was supplied the kitten guesses the MIME type of the destination argument (e.g. from its extension via utils.GuessMimeType, with special handling for kitty-supported text types). If guessing yields an empty string, it errors asking you to specify --mime manually.

Source

Thrown at kittens/clipboard/read.go:317

	outputs := make([]*Output, len(args))
	aliases, merr := parse_aliases(opts.Alias)
	if merr != nil {
		return merr
	}

	for i, arg := range args {
		outputs[i] = &Output{arg: arg, arg_is_stream: arg == "/dev/stdout" || arg == "/dev/stderr", ext: filepath.Ext(arg)}
		if len(opts.Mime) > i {
			outputs[i].mime_type = opts.Mime[i]
		} else {
			if outputs[i].arg_is_stream {
				outputs[i].mime_type = "text/plain"
			} else {
				outputs[i].mime_type = utils.GuessMimeType(outputs[i].arg)
			}
		}
		if outputs[i].mime_type == "" {
			return fmt.Errorf("Could not detect the MIME type for: %s use --mime to specify it manually", arg)
		}
	}

	defer func() {
		for _, o := range outputs {
			if o.dest != nil {
				o.cleanup()
			}
		}
	}()

	basic_metadata := map[string]string{"type": "read"}
	if opts.UsePrimary {
		basic_metadata["loc"] = "primary"
	}
	lp.OnInitialize = func() (string, error) {
		lp.QueueWriteString(encode(basic_metadata, "."))
		if opts.Password != "" {

View on GitHub (pinned to 6d5d0c4406)

Solutions

1. Pass --mime explicitly: `kitten clipboard get --mime application/octet-stream data.bin`
2. Name the destination with a recognized extension (e.g. .png, .txt, .json)
3. When scripting, first query available types and map them yourself before calling get

Example fix

# before
kitten clipboard get /tmp/clip.blob
# after
kitten clipboard get --mime image/png /tmp/clip.blob

# require a known extension or explicit --mime
case "$DEST" in *.png|*.txt|*.json) ;; *) MIME="${MIME:-application/octet-stream}";; esac
[ -n "$MIME" ] && set -- --mime "$MIME" "$@"

When it happens

Trigger: `kitten clipboard get data.bin` where .bin (or no extension) has no known MIME mapping; destination files with unusual or missing extensions that GuessMimeType does not recognize.

Common situations: Downloading clipboard blobs to extensionless temp files; custom binary formats; tools scripting getfile with generated filenames like /tmp/clip.$$.

Related errors

• Failed to encode image data to %s with error: %w
• The MIME type %s for %s not available on the clipboard
• Too much piped data
• Failed to read from STDIN pipe with error: %w
• Failed to create a temporary from STDIN pipe with error: %w

AI-assisted analysis of kovidgoyal/kitty@6d5d0c4406 (2026-08-27). Data as JSON: /api/errors/c55e08b4e046081e. Report an issue: GitHub.