Errors regarding non-existent files in pg_subtrans

G'day list.

I've recently upgraded a number of servers from PostgreSQL 9.2.5 to
9.3.1 and have started getting the following errors every couple of
hours along with some failed transactions. I have been unable to track
down any sort of rhyme or reason for the errors yet, so I figured I'd
check with the mailing list to see if I've potentially hit into a
potential bug. The errors look like the following:

ERROR could not access status of transaction 4179979
Could not open file "pg_subtrans/003F": No such file or directory.

Indeed, pg_subtrans/003F does not exist on the file system.

I have found similar errors mentioned on the list before a number of
years ago with a thread starting here:

http://www.postgresql.org/message-id/20111109150225.076c2f38@list.ru

A few details:

- the new database cluster was created by dumping global settings
using pg_dumpall and then dumping each database individually. Several
of the databases within this cluster have PostGIS installed and I
wanted to do a full PostGIS upgrade, which necessitated individual
dumps.

- this is the only database in a cluster of 14 databases that is
exhibiting the problem and it is sporadic at best. This database is
fairly write-intensive, and has been up since November 6th. In that
time, we've had 17 such errors.

- the pg_subtrans files mentioned in the log file do not exist on the
file system.

- I have rebuilt the cluster several times, as well as cleaned out the
pg_statistic table and run `VACUUM FULL ANALYZE` on every database in
case that was affecting it based on some similar threads back from the
PostgreSQL 8.4 days, but there was no affect and the errors still
occur.

Anyone have any suggestions or ideas? Thankfully these are dev systems
so I have some room to experiment and can post some more details as
necessary.

The following are the log file entries from one of the errors. Some
details have been sanitized for privacy reasons, but the overall lines
themselves are accurate.

Nov 10 10:14:02 dev-server postgres[29835]: [4-1] user=dev,db=dev
ERROR: could not access status of transaction 4179979
Nov 10 10:14:02 dev-server postgres[29835]: [4-2] user=dev,db=dev
DETAIL: Could not open file "pg_subtrans/003F": No such file or
directory.
Nov 10 10:14:02 dev-server postgres[29835]: [4-3] user=dev,db=dev
CONTEXT: SQL statement "SELECT 1 FROM ONLY
"typhon"."collection_batches" x WHERE "id" OPERATOR(pg_catalog.=) $1
FOR KEY SHARE OF x"
Nov 10 10:14:02 dev-server postgres[29835]: [4-4] user=dev,db=dev
STATEMENT: insert into raw (url, id) values ($1, $2)
Nov 10 10:14:02 dev-server postgres[29839]: [4-1] user=dev,db=dev
ERROR: could not access status of transaction 4179979
Nov 10 10:14:02 dev-server postgres[29839]: [4-2] user=dev,db=dev
DETAIL: Could not open file "pg_subtrans/003F": No such file or
directory.
Nov 10 10:14:02 dev-server postgres[29839]: [4-3] user=dev,db=dev
CONTEXT: SQL statement "SELECT 1 FROM ONLY
"typhon"."collection_batches" x WHERE "id" OPERATOR(pg_catalog.=) $1
FOR KEY SHARE OF x"
Nov 10 10:14:02 dev-server postgres[29839]: [4-4] user=dev,db=dev
STATEMENT: update listings set value_a=$1 where id=$2
Nov 10 10:14:02 dev-server postgres[29827]: [4-1] user=dev,db=dev
ERROR: could not access status of transaction 4179979
Nov 10 10:14:02 dev-server postgres[29827]: [4-2] user=dev,db=dev
DETAIL: Could not open file "pg_subtrans/003F": No such file or
directory.
Nov 10 10:14:02 dev-server postgres[29827]: [4-3] user=dev,db=dev
CONTEXT: SQL statement "SELECT 1 FROM ONLY
"typhon"."collection_batches" x WHERE "id" OPERATOR(pg_catalog.=) $1
FOR KEY SHARE OF x"

I can provide additional details like my postgresql.conf if it would
help, although it's fairly standard outside of tuning as provided by
pgtune.

Cheers and thanks, List.