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formerly vs. formally

formerly

[fawr-mer-lee] / ˈfɔr mər li /

adverb

in time past; in an earlier period or age; previously.

a custom formerly observed.
Obsolete. in time just past; just now.

formally

[fawr-muh-lee] / ˈfɔr mə li /

in a formal manner.

The store was formally opened on Tuesday.
as regards form; in form.

It may be formally correct, but it is substantively wrong.