What causes "Failed to read requested mime type {mime} with error: {e}" in kovidgoyal/kitty?

Only request MIME types you know may be present (or handle empty responses gracefully)

Failed to read requested mime type

Error message

Failed to read requested mime type {mime} with error: {e}

What it means

While fulfilling a clipboard read request, reading the requested MIME type from the clipboard provider (cp.get_mime) raised; kitty logs it and continues with the remaining MIME types, ending the response with DONE.

Solutions

Only request MIME types you know may be present (or handle empty responses gracefully)
Retry the read once — clipboard owner races are transient
Update kitty; provider-specific bugs get patched

Defensive patterns

Strategy: retry

Validate before calling

null  # cannot validate OS clipboard contents reliably beforehand

Try / catch

try:\n    cp.get_mime(mime, write_chunks)\nexcept Exception:\n    continue  # skip this MIME type, response still ends DONE

Prevention

Request only plausible MIME types
Retry once on transient clipboard-owner races

When it happens

Trigger: A read request asking for a MIME type the OS clipboard has no data for, or the OS clipboard API raising during retrieval (e.g. Wayland/X11 clipboard manager hiccup, image MIME missing).

Common situations: Clients requesting image/png when only text is present on servers that error instead of returning empty; races where the clipboard owner disappears mid-read.

Related errors

AI-assisted analysis of kovidgoyal/kitty@6d5d0c4406 (2026-08-27). Data as JSON: /api/errors/83f3d17da9b2890c. Report an issue: GitHub.

Appendix: source

Thrown at kitty/clipboard.py:681

        def write_chunks(data: bytes) -> None:
            assert w is not None
            mv = memoryview(data)
            while mv:
                w.screen.send_escape_code_to_child(ESC_OSC, rr.encode_response(payload=mv[:READ_RESPONSE_CHUNK_SIZE], mime=current_mime))
                mv = mv[READ_RESPONSE_CHUNK_SIZE:]

        for mime in rr.mime_types:
            current_mime = mime
            if mime == TARGETS_MIME:
                payload = ' '.join(cp.get_available_mime_types_for_paste()).encode('utf-8')
                if payload:
                    payload += b'\n'
                w.screen.send_escape_code_to_child(ESC_OSC, rr.encode_response(payload=payload, mime=current_mime))
                continue
            try:
                cp.get_mime(mime, write_chunks)
            except Exception as e:
                log_error(f'Failed to read requested mime type {mime} with error: {e}')
        w.screen.send_escape_code_to_child(ESC_OSC, rr.encode_response(status='DONE'))

    def reject_read_request(self, rr: ReadRequest) -> None:
        if rr.protocol_type is ProtocolType.osc_52:
            return self.fulfill_legacy_read_request(rr, False)
        w = get_boss().window_id_map.get(self.window_id)
        if w is not None:
            w.screen.send_escape_code_to_child(ESC_OSC, rr.encode_response(status='EPERM'))

    def fulfill_legacy_read_request(self, rr: ReadRequest, allowed: bool = True) -> None:
        cp = get_boss().primary_selection if rr.is_primary_selection else get_boss().clipboard
        w = get_boss().window_id_map.get(self.window_id)
        if w is not None:
            text = ''
            if cp.enabled and allowed:
                text = cp.get_text()
            loc = 'p' if rr.is_primary_selection else 'c'
            w.screen.send_escape_code_to_child(ESC_OSC, encode_osc52(loc, text))

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