redis-cli unix socket - import rcmd failing - redis

Question

I am using redis server 3.0.6 on ubuntu 16.04 desktop. Installed using
apt-get install redis-server
It was working fine for a long time. Today, when I tried to import a rcmd file using unix socket in redis-cli I am getting out of memory error.
$ sudo redis-cli -s /run/redis/redis.sock < a1.rcmd
Error: Out of memory
a1.rcmd contents:
SET Api:Server:Name "server1"
/etc/redis/redis.conf was confiured with /run/redis/redis.sock. All other configurations are default.
GET, SET commands with unix socket option are working fine.
If I run without unix socket, the redis-cli < a1.rcmd command is working fine.
What causes this error?
Will upgrade to latest version of redis resolve this? I dont see apt-get way to install latest redis version 5.
Any help would be really appreciated.
** EDIT **
Some more inputs and GDB logs.
$ which redis-server
/usr/bin/redis-server
$ sudo service redis-server status
● redis-server.service - Advanced key-value store
Loaded: loaded (/lib/systemd/system/redis-server.service; enabled; vendor preset: enabled)
Active: active (running) since Mon 2018-12-17 11:29:14 EST; 16min ago
Docs: http://redis.io/documentation,
man:redis-server(1)
Process: 8986 ExecStopPost=/bin/run-parts --verbose /etc/redis/redis-server.post-down.d (code=exited, status=0/SUCCESS)
Process: 8981 ExecStop=/bin/kill -s TERM $MAINPID (code=exited, status=0/SUCCESS)
Process: 8977 ExecStop=/bin/run-parts --verbose /etc/redis/redis-server.pre-down.d (code=exited, status=0/SUCCESS)
Process: 9001 ExecStartPost=/bin/run-parts --verbose /etc/redis/redis-server.post-up.d (code=exited, status=0/SUCCESS)
Process: 8997 ExecStart=/usr/bin/redis-server /etc/redis/redis.conf (code=exited, status=0/SUCCESS)
Process: 8992 ExecStartPre=/bin/run-parts --verbose /etc/redis/redis-server.pre-up.d (code=exited, status=0/SUCCESS)
Main PID: 9000 (redis-server)
Tasks: 3
Memory: 884.0K
CPU: 304ms
CGroup: /system.slice/redis-server.service
└─9000 /usr/bin/redis-server 127.0.0.1:637
$ sudo gdb /usr/bin/redis-server 9000
GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.5) 7.11.1
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
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<http://www.gnu.org/software/gdb/bugs/>.
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Reading symbols from /usr/bin/redis-server...(no debugging symbols found)...done.
Attaching to program: /usr/bin/redis-server, process 9000
[New LWP 9002]
[New LWP 9003]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
0x00007fe8f5158a13 in epoll_wait () at ../sysdeps/unix/syscall-template.S:84
84 ../sysdeps/unix/syscall-template.S: No such file or directory.
(gdb) continue
Continuing.
After this step I ran following command in another terminal:
$ sudo redis-cli -s /run/redis/redis.sock < a1.rcmd
Segmentation fault (core dumped)
(gdb) bt
#0 0x00007fe8f5158a13 in epoll_wait () at ../sysdeps/unix/syscall-template.S:84
#1 0x000055b238abe15f in aeProcessEvents ()
#2 0x000055b238abe58b in aeMain ()
#3 0x000055b238abd204 in main ()
(gdb) info registers
rax 0xfffffffffffffffc -4
rbx 0x7fe8f48e5300 140638512108288
rcx 0x7fe8f5158a13 140638520969747
rdx 0x1060 4192
rsi 0x7fe8f4910000 140638512283648
rdi 0x3 3
rbp 0x7fe8f487b068 0x7fe8f487b068
rsp 0x7ffd9a5ca920 0x7ffd9a5ca920
r8 0x284 644
r9 0x284 644
r10 0x64 100
r11 0x293 659
r12 0x7ffd9a5caae8 140727193217768
r13 0x7fe8f480e1a0 140638511227296
r14 0x7fe8f48101f0 140638511235568
r15 0xfffffffe 4294967294
rip 0x7fe8f5158a13 0x7fe8f5158a13 <epoll_wait+51>
eflags 0x293 [ CF AF SF IF ]
cs 0x33 51
ss 0x2b 43
ds 0x0 0
es 0x0 0
fs 0x0 0
gs 0x0 0
(gdb)