adchkcfg.sh Diff Tool Error

Hi,
Ran adchkcfg.sh on the database tier and saw this in its logfile:

Starting AutoConfig at Tue Aug 27 15:39:55 2013
Using adconfig.pl version 120.26.12010000.5

AC-60002: Diff Tool Error: File  not found.
Raised by oracle.apps.ad.autoconfig.HtmlDiffReport

AC-60000: Diff Tool Error: Error in reading or creating file .
Exception:  (No such file or directory)
Raised by oracle.apps.ad.autoconfig.HtmlDiffReport

StackTrace:
java.io.FileNotFoundException:  (No such file or directory)
    at java.io.FileInputStream.open(Native Method)
    at java.io.FileInputStream.<init>(Unknown Source)
    at java.io.FileInputStream.<init>(Unknown Source)
    at java.io.FileReader.<init>(Unknown Source)
    at oracle.apps.ad.autoconfig.HtmlDiffReport.isPwdPresent(HtmlDiffReport.java:1809)