You can always just delete CHDK from your camera's card and start over with a fresh installation of a new version.

If you want to keep your settings, just extract the newer version of CHDK over your old version; your settings will be kept. They reside in CCHDK.CFG, CCHDK3.CFG and CCHDK4.CFG in the CHDK folder and no default config file is in a CHDK archive file, so they won't get overwritten.

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