Known Bugs

The Linux NFS4 kernel client implementation is not free of bugs. Below we list the bugs we know of:

NFS4 I/O Fails after Server or Network Downtime

After a file server reboot or fail-over in case of high-available file services, or after the network at ETH experiences problems, it happens that pending I/O on any path on NFS4 mounted shares will fail with an error instead of recovering when the server is reachable again.


  • Forefox, Thunderbird or other applications that relay on access to a home directory randomly crash.
  • Gnome becomes unresponsive.

Reason and Remedy

A buggy commit in 4.3 in the linux kernel in 2015 causes this bug. Red Hat back-ported it with the 7.3 update of RHEL7.

It was fixed upstream at in the following kernels:

  • 5.2 and newer
  • 4.19.81 (longterm) or newer
  • 4.14.151 (longterm) or newer
  • 4.9.198 (longterm) or newer
  • 4.4.198(longterm) or newer

The patch that fixes this issue for 4.x, 5.0 and 5.1 kernels:

ipv4: Return -ENETUNREACH if we cant create route but saddr is valid

Affected Distributions

  • All Ubuntu, Fedora, CentOS and RHEL systems (and probably many more) with a 3.x, 4.x, 5.0 or 5.1 kernel

Fixes in Distributions

NFS 4.1 Client Hangs after Network Downtime

After a network outage an NFS4 client using 4.1 or 4.2 has a high probability to hang permanently on one or several mounted paths.

Affected Distributions

  • RHEL and CentOS 7

This behavior has also been reported for unspecified newer Ubuntu installations.


Avoid using 4.1 and 4.2 and switch to version 4.0.
I Attachment History Action Size Date Who Comment
Unknown file formatext disco-proposed-kernel r1 manage 0.1 K 2019-12-04 - 11:35 ThomasBerchtold  
Unknown file formatpatch nfs.patch r1 manage 3.4 K 2019-11-05 - 16:39 StefanWalter Patch for 4.x, 5.0 and 5.1 kernels

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