Cannot set user id: Resource temporarily unavailable while trying to login or su as a local user in CentOS

If you encounter this error while logging on or su --login as a user,

"cannot set user id: Resource temporarily unavailable" while trying to login or su as a local user.

In CentOS 6, the reason for this error is that the the user’s the number of executing threads has reached the nproc resource limit. You can solve the issues

You can edit /etc/security/limits.d/90-nproc.conf which is

# Default limit for number of user's processes to prevent
# accidental fork bombs.
# See rhbz #432903 for reasoning.

*          soft    nproc     1024
user1       soft    nproc    10240

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1. Cannot set user id: Resource temporarily unavailable while trying to login or su as a local user in CentOS