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Article Id 192914
This article addresses an issue with the synchronization between FortiMail and NAS/NFS where the FortiMail shows the message “failed to mount” after an upgrade to 5.4.x

The FortiMail in versions v5.3.x and earlier with NAS/NFS synchronized shows the following messages after it has been upgraded to v5.4.x:
nasd: failed to mount /var/spool/home.remote
nasd: failed to mount NAS for build

This issue occurs because the FortiMail on version v5.3.x and earlier is compatible with NFSv3 or earlier.  However, v5.4.x is only compatible with NFSv4.

To solve the issue, upgrade the NAS NFSv3 (or earlier) to the NFSv4.

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