CASTEP GO fails after SCF completed successfully

I am encountering an error when perfoming a GO in CASTEP. After the SCF is finished CASTEP runs in an error giving fortran error codes (see below). I appreciate any hint.


BFGS: Geometry optimization completed successfully.

================================================================================
BFGS: Final Configuration:
================================================================================
[...]
BFGS: Final Enthalpy = -5.85330255E+004 eV
BFGS: Final = 5879.70243 cm-1


******************************** Symmetrised Forces ********************************
* *
* Cartesian components (eV/A) *
* -------------------------------------------------------------------------------- *

[...]

forrtl: No such file or directory
forrtl: No such file or directory
forrtl: No such file or directory
forrtl: severe (28): CLOSE error, unit 11, file "Unknown"
Image PC Routine Line Source  
castepexe.exe 0000000000467042 for__io_return Unknown Unknown
castepexe.exe 000000000048864A for_close Unknown Unknown
castepexe.exe 0000000002A16993 Unknown Unknown Unknown
castepexe.exe 00000000029E0BBB Unknown Unknown Unknown
castepexe.exe 00000000029BC47D Unknown Unknown Unknown
castepexe.exe 00000000004B7F3F Unknown Unknown Unknown
castepexe.exe 0000000000456B1E main Unknown Unknown
libc-2.17.so 00007FA7EA3E8C05 __libc_start_main Unknown Unknown
castepexe.exe 0000000000456A29 Unknown Unknown Unknown
forrtl: severe (28): CLOSE error, unit 11, file "Unknown"
Image PC Routine Line Source  
castepexe.exe 0000000000467042 for__io_return Unknown Unknown
castepexe.exe 000000000048864A for_close Unknown Unknown
castepexe.exe 0000000002A16993 Unknown Unknown Unknown
castepexe.exe 00000000029E0BBB Unknown Unknown Unknown
castepexe.exe 00000000029BC47D Unknown Unknown Unknown
castepexe.exe 00000000004B7F3F Unknown Unknown Unknown
castepexe.exe 0000000000456B1E main Unknown Unknown
libc-2.17.so 00007F2F9DC6EC05 __libc_start_main Unknown Unknown
castepexe.exe 0000000000456A29 Unknown Unknown Unknown
forrtl: severe (28): CLOSE error, unit 11, file "Unknown"
Image PC Routine Line Source  
castepexe.exe 0000000000467042 for__io_return Unknown Unknown
castepexe.exe 000000000048864A for_close Unknown Unknown
castepexe.exe 0000000002A16993 Unknown Unknown Unknown
castepexe.exe 00000000029E0BBB Unknown Unknown Unknown
castepexe.exe 00000000029BC47D Unknown Unknown Unknown
castepexe.exe 00000000004B7F3F Unknown Unknown Unknown
castepexe.exe 0000000000456B1E main Unknown Unknown
libc-2.17.so 00007F9FC8092C05 __libc_start_main Unknown Unknown
castepexe.exe 0000000000456A29 Unknown Unknown Unknown

Last known process information:
===============================
Name: castepexe.exe
Umask: 0002
State: R (running)
Tgid: 28289
Ngid: 0
Pid: 28289
PPid: 28285
TracerPid: 0
Uid: 1004 1004 1004 1004
Gid: 1004 1004 1004 1004
FDSize: 64
Groups: 1004
VmPeak: 4465336 kB
VmSize: 2804540 kB
VmLck: 0 kB
VmPin: 0 kB
VmHWM: 4154580 kB
VmRSS: 2495536 kB
RssAnon: 2457908 kB
RssFile: 18956 kB
RssShmem: 18672 kB
VmData: 2495296 kB
VmStk: 3824 kB
VmExe: 150104 kB
VmLib: 33460 kB
VmPTE: 5364 kB
VmSwap: 0 kB
Threads: 1
SigQ: 0/127278
SigPnd: 0000000000000000
ShdPnd: 0000000000000000
SigBlk: 0000000000000000
SigIgn: 0000000000100000
SigCgt: 00000001800046ae
CapInh: 0000000000000000
CapPrm: 0000000000000000
CapEff: 0000000000000000
CapBnd: 0000001fffffffff
CapAmb: 0000000000000000
Seccomp: 0
Cpus_allowed: 1
Cpus_allowed_list: 0
Mems_allowed: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000001
Mems_allowed_list: 0
voluntary_ctxt_switches: 92990
nonvoluntary_ctxt_switches: 20332270