Yes, Have you looked in that file? Edit it and change the following line.
and change it to the following:
upload_max_filesize = 8M
This should solve your problems with the upgrade. Also you might want to look at increasing it more if you store large documents in the Documents module. just size it to the maximum document size you want to allow to be uploaded to the system. Do not lower it below 16M for upgrades as some files may grow to be that big with major updates.
upload_max_filesize = 16M