Mismatch: X:462 doesn't match requested X:2
X:2 not found in http://thesession.org/tunes/8437

Error exit status 256; here are some files to check:
[P=get.cgi V=1/1 B=0 scale=0.60 512x512 ]
filesizedescription
Tune-3869-8437.abc 0 ABC music file with the extracted tune(s)
Tune-3869-8437.txt 0 Plain-text file with the extracted tune(s)
Tune-3869-get.log 3598 Log file, useful mostly for debugging
These files should be available for 24 hours.