kovidgoyal/kitty · warning

Failed to write to disk-cache file

Error message

Failed to write to disk-cache file

What it means

pwrite() to the disk-cache file failed with an errno other than EINTR/EAGAIN while the background thread flushed a dirty scrollback entry. The entry's offset is reset to -1 so it can be retried at a new offset later; scrollback stays in memory. ENOSPC is the most common cause.

Source

Thrown at kitty/disk-cache.c:463

}

static bool
write_dirty_entry(DiskCache *self) {
    size_t left = self->currently_writing.val.data_sz;
    uint8_t *p = self->currently_writing.val.data;
    if (self->currently_writing.val.pos_in_cache_file < 0) {
        self->currently_writing.val.pos_in_cache_file = self->end_of_data_offset;
        if (self->currently_writing.val.pos_in_cache_file < 0) {
            perror("Failed to seek in disk cache file");
            return false;
        }
    }
    off_t offset = self->currently_writing.val.pos_in_cache_file;
    while (left > 0) {
        ssize_t n = pwrite(self->cache_file_fd, p, left, offset);
        if (n < 0) {
            if (errno == EINTR || errno == EAGAIN) continue;
            perror("Failed to write to disk-cache file");
            self->currently_writing.val.pos_in_cache_file = -1;
            return false;
        }
        if (n == 0) {
            fprintf(stderr, "Failed to write to disk-cache file with zero return\n");
            self->currently_writing.val.pos_in_cache_file = -1;
            return false;
        }
        left -= n;
        p += n;
        offset += n;
        self->end_of_data_offset = MAX(self->end_of_data_offset, offset);
    }
    return true;
}

static void
retire_currently_writing(DiskCache *self) {

View on GitHub (pinned to 6d5d0c4406)

Solutions

1. Free space on the filesystem holding the cache (df -h).
2. Delete kitty's disk cache directory with kitty closed, so it starts fresh.
3. Reduce scrollback history size to lower write volume.
4. If EBADF during shutdown, it's benign — upgrade kitty.

df -h "${XDG_CACHE_HOME:-$HOME/.cache}"  # check free space before long scrollback-heavy sessions

When it happens

Trigger: write_loop -> write_dirty_entry -> pwrite returning -1, e.g. ENOSPC (cache filesystem full), EBADF (cache fd closed during shutdown), EIO (disk error).

Common situations: Full home/tmpfs partition with heavy scrollback usage; cache file deleted while running; failing disk.

Related errors

• Failed to open second file for defrag of disk cache
• Failed to allocate space for new disk cache file during defr
• Failed to copy data to new disk cache file during defrag
• Failed to seek in disk cache file
• This must be run as kitten ask

AI-assisted analysis of kovidgoyal/kitty@6d5d0c4406 (2026-08-27). Data as JSON: /api/errors/a5d1fda4cec46162. Report an issue: GitHub.