regression: cannot modify files on 12.04 nfs server with a 14.04 nfs client - filesystem read only

[no!chance]

With standard settings, nfs maps all user ids to nobody/nogroup.

With vers=3 as mount option, the nfs client shows the right userids,
but when I try to edit a file, nfs reports the file system as READ ONLY, whiuch is not correct.

Mount command reports this file system as READ WRITE and I am owner of all file on this share. I see no reason why these files or the filesystem should be read only. All other version of ubuntu have no problems reading and writing files on a nfs network share, at least 13.10 works.

For me, Ubuntu 14.04 LTS is not usable at all - especially for a production system!

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: nfs-common 1:1.2.8-6ubuntu1
ProcVersionSignature: Ubuntu 3.13.0-24.46-generic 3.13.9
Uname: Linux 3.13.0-24-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.14.1-0ubuntu3
Architecture: amd64
CurrentDesktop: Unity
Date: Tue Apr 22 22:16:27 2014
EcryptfsInUse: Yes
InstallationDate: Installed on 2014-04-05 (17 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Beta amd64 (20140326)
ProcEnviron:
 LANGUAGE=de_DE
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: nfs-utils
UpgradeStatus: No upgrade log present (probably fresh install)

[no!chance (ralf-fehlau)]

Even with vers=4 nfs reports "file system is read only".

[no!chance (ralf-fehlau)]

Sorry, restarting nfs-kernel-server on Ubuntu 12.04 solves this problem.
But I don't know, why. I do not find any error message regarding nfs in the logs. Perhaps a 12.04 problem?