Error when activating a config file: "Error: 17000 - Error opening file/quest/005/splex/state/o.S (4300749)

When trying to activate a new config, it fails with the below errors in the event log:

Logging user command: oracle activate config
quest_config.file2
Process launched: sp_tconf (for o.SID1) [pid = 14370]
Notice: Oracle env - SID1:/u01/app/oracle/product/9.2
[sp_tconf(pdb)/14370]
Compiling a configuration file: datasrc - o.SID1; file -
quest_config.file2
Notice: Oracle version 92 [sp_tconf(osp)/14370]
Notice: New activation id 187 [sp_tconf/14370]
Error: 17000 - Error opening file
/quest/005/splex/state/o.SID1-objcache.189: No such file or directory.
[sp_tconf(osp)/14370]
Config compilation completed: datasrc - o.SID1; file -
quest_config.file2
Bad config file: file - quest_config.file2; INT Error, cant
open or read object cache file. See log for more details - ReadObjCache
Process exited sp_tconf (for o.SID1) [pid = 14370] -
exit(1)

In later versions of SharePlex the event log entries may be slightly different but convey the same issue:

Activation: 17006 - Cannot open object cache: Input/output: <$SP_SYS_VARDIR>/state/o.sid-objcache_sp_conf.x: open() failed  (activating sid sidname) [module osp]

Error    2011-02-09 10:36:25.917163 29607 4136249952

Activation: 17006 - Cannot open object cache: Input/output: <$SP_SYS_VARDIR>/state/o.sid-objcache_sp_conf.x: open() failed  (activating sid sidname) [module osp]

Error    2011-02-09 10:36:25.951627 29607 4136249952 Compile of "config file name" for sid o.sid failed: INT Error, can't open or read object cache file. See log for more details - ReadObjCache

Info     2011-02-09 10:36:26.046533 19560 4136556224 Activation exited with code=1, pid = 29607  (activating sid sidname)