In 6.0, minicom is no longer SGID "uucp", but /var/lock directory is only group writeable and it's group is uucp, so minicom cannot create the /var/lock/LCK..modem file so it fails. The only workaround is to run "minicom -s" as root to change the lock directory, but then other modem software (such as ppp dialers) cannot know if the modem is being used.
Verified that in 6.0, /var/lock is indeed not world-writable and therefore minicom does have problems creating the lock file.
Fixed in dist-6.1 minicom-1.82-6.
*** Bug 3087 has been marked as a duplicate of this bug. *** the default perms on the minicom binary do not allow it to create lockfiles in /var/lock since /var/lock is not world writable +t. 5.2's minicom was set gid uucp as this would allow it to create lock files in /var/lock bad news: normal uses cannot launch minicom