This article is from the Food Preserving FAQ, by Eric Decker firstname.lastname@example.org with numerous contributions by others.
---- PROBLEMS WITH HOME-CANNED FOODS-----------
Even when you follow directions, occasionally you may have problems
with home-canned foods. Many of these problems can be traced to use of
non-standard canning jars, lids and rings or use of
other-than-recommended canning equipment or procedures. Checking your
equipment and reviewing current canning recommendations can go a long
way towards preventing potential problems. If you do have a problem,
you may be able to determine the cause and prevent its reoccurrence by
consulting this "trouble-shooter's guide".