Troubleshoot NFS Azure file shares


CentOS referenced in this article is a Linux distribution and will reach End Of Life (EOL). Consider your use and plan accordingly. For more information, see CentOS End Of Life guidance.

This article lists common issues related to NFS Azure file shares and provides potential causes and workarounds.


The content of this article only applies to NFS shares. To troubleshoot SMB issues in Linux, see Troubleshoot Azure Files problems in Linux (SMB). NFS Azure file shares aren't supported for Windows.

Applies to

File share type SMB NFS
Standard file shares (GPv2), LRS/ZRS
Standard file shares (GPv2), GRS/GZRS
Premium file shares (FileStorage), LRS/ZRS

chgrp "filename" failed: Invalid argument (22)

Cause 1: idmapping isn't disabled

Because Azure Files disallows alphanumeric UID/GID, you must disable idmapping.

Cause 2: idmapping was disabled, but got re-enabled after encountering bad file/dir name

Even if you correctly disable idmapping, it can be automatically re-enabled in some cases. For example, when Azure Files encounters a bad file name, it sends back an error. Upon seeing this error code, an NFS 4.1 Linux client decides to re-enable idmapping, and sends future requests with alphanumeric UID/GID. For a list of unsupported characters on Azure Files, see this article. Colon is one of the unsupported characters.


Make sure you've disabled idmapping and that nothing is re-enabling it. Then perform the following steps:

  1. Unmount the share.

  2. Disable idmapping with:

    sudo echo Y > /sys/module/nfs/parameters/nfs4_disable_idmapping
  3. Mount the share back.

  4. If running rsync, run rsync with the —numeric-ids argument from a directory that doesn't have a bad directory or file name.

Unable to create an NFS share

Cause: Unsupported storage account settings

NFS is only available on storage accounts with the following configuration:


Follow the instructions in How to create an NFS share.

Can't connect to or mount an NFS Azure file share

Cause 1: Request originates from a client in an untrusted network/untrusted IP

Unlike SMB, NFS doesn't have user-based authentication. The authentication for a share is based on your network security rule configuration. To ensure that clients only establish secure connections to your NFS share, you must use either the service endpoint or private endpoints. To access shares from on-premises in addition to private endpoints, you must set up a VPN or ExpressRoute connection. IPs added to the storage account's allowlist for the firewall are ignored. You must use one of the following methods to set up access to an NFS share:

  • Service endpoint

    • Accessed by the public endpoint.

    • Only available in the same region.

    • You can't use VNet peering for share access.

    • You must add each virtual network or subnet individually to the allowlist.

    • For on-premises access, you can use service endpoints with ExpressRoute, point-to-site, and site-to-site VPNs. We recommend using a private endpoint because it's more secure.

      The following diagram depicts connectivity using public endpoints:

      Diagram of public endpoint connectivity.

  • Private endpoint

    • Access is more secure than the service endpoint.

    • Access to NFS share via private link is available from within and outside the storage account's Azure region (cross-region, on-premises).

    • Virtual network peering with virtual networks hosted in the private endpoint give the NFS share access to the clients in peered virtual networks.

    • You can use private endpoints with ExpressRoute, point-to-site VPNs, and site-to-site VPNs.

      Diagram of private endpoint connectivity.

Cause 2: Secure transfer required is enabled

NFS Azure file shares don't currently support double encryption. Azure provides a layer of encryption for all data in transit between Azure datacenters using MACSec. You can only access NFS shares from trusted virtual networks and over VPN tunnels. No extra transport layer encryption is available on NFS shares.


Disable Secure transfer required in your storage account's configuration blade.

Screenshot that shows the storage account configuration blade, disabling secure transfer required.

Cause 3: nfs-utils, nfs-client or nfs-common package isn't installed

Before running the mount command, install the nfs-utils, nfs-client, or nfs-common package.

To check if the NFS package is installed, run:

The same commands in this section apply to CentOS and Oracle Linux.

sudo rpm -qa | grep nfs-utils


If the package isn't installed, install the package using your distro-specific command.

The same commands in this section apply to CentOS and Oracle Linux.

OS Version 7.X

sudo yum install nfs-utils

OS Version 8.X or 9.X

sudo dnf install nfs-utils

Cause 4: Firewall blocking port 2049

The NFS protocol communicates to its server over port 2049. Make sure that this port is open to the storage account (the NFS server).


Verify that port 2049 is open on your client by running the following command. If the port isn't open, open it.

sudo nc -zv <storageaccountnamehere> 2049

Cause 5: Storage account deleted

If you're unable to mount the file share due to error: connection timed out, the storage account containing the file share might be deleted accidentally.


Recover the storage account. Then, delete and re-create the private endpoint so it's associated with the new storage account resource ID.

ls hangs for large directory enumeration on some kernels

Cause: A bug was introduced in Linux kernel v5.11 and was fixed in v5.12.5

Some kernel versions have a bug that causes directory listings to result in an endless READDIR sequence. Small directories where all entries can be shipped in one call don't have this problem. The bug was introduced in Linux kernel v5.11 and was fixed in v5.12.5. So anything in between has the bug. RHEL 8.4 has this kernel version.

Workaround: Downgrade or upgrade the kernel

Downgrading or upgrading the kernel to anything outside the affected kernel should resolve the issue.

System commands fail with the "File not found" error


Linux 32-bit applications that rely on inode numbers might not work as expected with Azure Files due to the formatting of the 64-bit inode numbers generated by the NFS service.


To resolve this issue, use one of the following methods:

  • Compress the 64-bit inode numbers to 32 bits by using the nfs.enable_ino64=0 kernel boot option.

  • Set the module parameter by adding options nfs enable_ino64=0 to the /etc/modprobe.d/nfs.conf file and rebooting the VM.

You can also persist this kernel boot option in the grub.conf file. For more information, see the documentation for your Linux distribution.

Need help?

If you still need help, contact support to get your problem resolved quickly.

See also

Contact us for help

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