hashicorp/vagrant · error · Vagrant::Errors::NFSDupePerms

You have attempted to export the same nfs host path at %{hos

Error message

You have attempted to export the same nfs host path at %{hostpath} with
different nfs permissions. Please pick one permission and reload your guest.

What it means

Vagrant::Errors::NFSDupePerms raised at plugins/hosts/linux/cap/nfs.rb:151. While collapsing synced folders that share a hostpath (group_by on :hostpath), the Linux cap checks that every group member has identical linux__nfs_options; /etc/exports cannot carry two permission sets for one directory, so a mismatch raises naming the path. Comparison is plain array equality — element order matters.

Source

Thrown at plugins/hosts/linux/cap/nfs.rb:151

        # Takes a hash of folders and removes any duplicate exports that
        # share the same hostpath to avoid duplicate entries in /etc/exports
        # ref: GH-4666
        def self.folder_dupe_check(folders)
          return_folders = {}
          # Group by hostpath to see if there are multiple exports coming
          # from the same folder
          export_groups = folders.values.group_by { |h| h[:hostpath] }

          # We need to check that each group key only has 1 value,
          # and if not, check each nfs option. If all nfs options are the same
          # we're good, otherwise throw an exception
          export_groups.each do |path,group|
            if group.size > 1
              # if the linux nfs options aren't all the same throw an exception
              group1_opts = group.first[:linux__nfs_options]

              if !group.all? {|g| g[:linux__nfs_options] == group1_opts}
                raise Vagrant::Errors::NFSDupePerms, hostpath: group.first[:hostpath]
              else
                # if they're the same just pick the first one
                return_folders[path] = group.first
              end
            else
              # just return folder, there are no duplicates
              return_folders[path] = group.first
            end
          end
          return_folders
        end

        def self.nfs_cleanup(remove_ids)
          return if !File.exist?(NFS_EXPORTS_PATH)

          editor = Vagrant::Util::StringBlockEditor.new(nfs_exports_content)
          remove_ids = Array(remove_ids)

View on GitHub (pinned to 35f3160f4a)

Solutions

Make linux__nfs_options identical — same elements in the same order — for every synced folder sharing that host path
Or consolidate to a single synced_folder entry for the shared directory
Run `vagrant reload` after fixing the Vagrantfile

Example fix

# before — same host path, two different option sets
config.vm.synced_folder "/srv/shared", "/a", type: "nfs",
  linux__nfs_options: ["rw","no_subtree_check","all_squash"]
config.vm.synced_folder "/srv/shared", "/b", type: "nfs",
  linux__nfs_options: ["ro","no_subtree_check"]
# after — one consistent option set for /srv/shared
config.vm.synced_folder "/srv/shared", "/a", type: "nfs",
  linux__nfs_options: ["rw","no_subtree_check","all_squash"]
config.vm.synced_folder "/srv/shared", "/b", type: "nfs",
  linux__nfs_options: ["rw","no_subtree_check","all_squash"]

Defensive patterns

Strategy: validation

Validate before calling

# Pre-flight: assert one option set per host path before vagrant up
folders = { "/a" => { hostpath: "/srv/shared", linux__nfs_options: ["rw","no_subtree_check"] },
           "/b" => { hostpath: "/srv/shared", linux__nfs_options: ["ro","no_subtree_check"] } }
folders.group_by { |_, o| File.expand_path(o[:hostpath]) }.each do |path, list|
  uniq = list.map { |_, o| o[:linux__nfs_options] }.uniq
  abort "#{path} exported with #{uniq.size} different nfs option sets" if uniq.size > 1
end

Try / catch

begin
  HostLinux::Cap::NFS.nfs_export(env, ui, id, ips, folders)
rescue Vagrant::Errors::NFSDupePerms => e
  puts "conflicting options for #{e.data[:hostpath]} — unify linux__nfs_options"
  raise
end

Prevention

Define linux__nfs_options once (a constant) and reuse it for shared paths
Remember array order matters in the equality check
Prefer one synced_folder per shared host directory

When it happens

Trigger: A Vagrantfile where two or more `type: "nfs"` synced_folders resolve to the same host path but their linux__nfs_options arrays differ in content or order (e.g. one with defaults, one customized; rw vs ro; different uid/gid mappings).

Common situations: Copy-pasting a synced_folder block and tweaking options; multi-machine Vagrantfiles sharing a host dir with per-machine options; identical option sets listed in different orders (still unequal via ==).

Related errors

AI-assisted analysis of hashicorp/vagrant@35f3160f4a (2026-08-21). Data as JSON: /api/errors/d942b4983699073f. Report an issue: GitHub.