Canning squash or pumpkin puree isn't recommended: http://www.uga.edu/nchfp/tips/fall/pumpkins.html
Canning pumpkin butter or mashed or pureed pumpkin is NOT recommended.
Home canning is not recommended for pumpkin butter or any mashed or pureed pumpkin or winter squash. In 1989, the USDA's Extension Service published the Complete Guide to Home Canning that remains the basis of Extension recommendations today, found in the September 1994 revision. The only directions for canning pumpkin and winter squash are for cubed pulp. In fact, the directions for preparing the product include the statement, "Caution: Do not mash or puree." More information can be found here: http://www.uga.edu/nchfp/publications/uga/pumpkin_butter.html
Remember that just because you can seal a jar doesn't mean that what's inside it is safe to eat (read: that the bacteria and spores have been killed).
Home canning is not recommended for pumpkin butter or any mashed or pureed pumpkin or winter squash. In 1989, the USDA's Extension Service published the Complete Guide to Home Canning that remains the basis of Extension recommendations today, found in the September 1994 revision. The only directions for canning pumpkin and winter squash are for cubed pulp. In fact, the directions for preparing the product include the statement, "Caution: Do not mash or puree." More information can be found here: http://www.uga.edu/nchfp/publications/uga/pumpkin_butter.html
Remember that just because you can seal a jar doesn't mean that what's inside it is safe to eat (read: that the bacteria and spores have been killed).