What causes "overlapping mounts not supported: %w" in abiosoft/colima?

Drop the redundant ancestor mount and keep only the deepest path you need

overlapping mounts not supported: %w

Error message

overlapping mounts not supported: %w

What it means

Error from checkOverlappingMounts during Lima config generation: two mounts' cleaned paths prefix each other (strings.HasPrefix both ways), which Lima cannot handle (lima-vm/lima#302). It fires only when conf.Mounts is non-empty; an empty/nil slice gets the default '~' writable mount instead.

Source

Thrown at environment/vm/lima/yaml.go:387

		})
	}

	// grow partition in case disk size has increased
	l.Provision = append(l.Provision, limaconfig.Provision{
		Mode:   limaconfig.ProvisionModeSystem,
		Script: "resize2fs " + diskByLabelPath(config.CurrentProfile().ID) + " || true",
	})

	/* end */

	if conf.Mounts != nil && len(conf.Mounts) == 0 {
		l.Mounts = append(l.Mounts,
			limaconfig.Mount{Location: "~", Writable: true},
		)
	} else {
		// overlapping mounts are problematic in Lima https://github.com/lima-vm/lima/issues/302
		if err = checkOverlappingMounts(conf.Mounts); err != nil {
			err = fmt.Errorf("overlapping mounts not supported: %w", err)
			return
		}

		for _, m := range conf.Mounts {
			var location, mountPoint string
			location, err = util.CleanPath(m.Location)
			if err != nil {
				return
			}
			mountPoint, err = util.CleanPath(m.MountPoint)
			if err != nil {
				return
			}

			mount := limaconfig.Mount{Location: location, MountPoint: mountPoint, Writable: m.Writable}

			l.Mounts = append(l.Mounts, mount)
		}

View on GitHub (pinned to c3a5f9184d)

Solutions

Drop the redundant ancestor mount and keep only the deepest path you need
Reorder your intent: mount the common parent once with the desired writability instead of layering children
If you only want the home directory, pass no --mount at all — colima defaults to mounting '~' writable
Ensure paths are cleaned/absolute so '~/foo' and '/Users/x/foo' are not accidentally compared as distinct

Example fix

# before
colima start --mount ~/src:ro --mount ~/src/writable
# after: single mount, adjust writability at the parent
colima start --mount ~/src

Defensive patterns

Strategy: validation

Validate before calling

// mirror checkOverlappingMounts before start
func mountsOverlap(mounts []config.Mount) bool {
    paths := make([]string, 0, len(mounts))
    for _, m := range mounts {
        p, _ := util.CleanPath(firstNonEmpty(m.MountPoint, m.Location))
        paths = append(paths, p)
    }
    for i := range paths {
        for j := i + 1; j < len(paths); j++ {
            if strings.HasPrefix(paths[i], paths[j]) || strings.HasPrefix(paths[j], paths[i]) {
                return true
            }
        }
    }
    return false
}

Try / catch

In Go: if err := checkOverlappingMountsLike(conf.Mounts); err != nil { reject config early with both offending paths } — the start-time error already names the pair; surface it verbatim.

Prevention

Design mounts as a flat set of disjoint subtrees — never nest one mount under another
Remember '~' (the default) overlaps every home-relative path: pass explicit mounts or none, not both
Clean paths before comparing so '~' vs absolute duplicates don't slip through your own checks

When it happens

Trigger: Passing mounts where one location/mount point is a path prefix of another: '~' together with '~/projects', '/Users/me' with '/Users/me/src', or a mountPoint nested under another mount's mountPoint.

Common situations: 'colima start --mount ~/src --mount ~/src/subdir' for IDE convenience; adding a deeper writable mount on top of a read-only parent mount; migrating docker-machine/VirtualBox style nested shares.

Related errors

AI-assisted analysis of abiosoft/colima@c3a5f9184d (2026-08-15). Data as JSON: /api/errors/dbe49b88473fc0ac. Report an issue: GitHub.