Zbigniew and I have both reported cases of "TransactionItem not found for key" or "TransactionItem state is not set" errors in two other bugs: https://bugzilla.redhat.com/show_bug.cgi?id=1627534#c1 (Zbigniew) https://bugzilla.redhat.com/show_bug.cgi?id=1642796#c19 (me) which turned out to be not the same as the other reports in those bugs, but a distinct case: this error can occur if the RPM database has multiple entries for a package when a transaction involving that package is run, as can be the case if a *previous* transaction went wrong somehow. So if you update from foo-1.0 to foo-2.0, only that transaction fails early and the RPM db winds up still having both 'foo-1.0' and 'foo-2.0' entries, then when you go to update to 'foo-3.0', the transaction may end with one of these errors. Per https://bugzilla.redhat.com/show_bug.cgi?id=1642796#c25 , jmracek has written a fix for this case: https://github.com/rpm-software-management/dnf/pull/1260
libdnf-0.22.3-1.fc29 dnf-4.0.9-1.fc29 dnf-plugins-core-4.0.2-1.fc29 dnf-plugins-extras-4.0.0-1.fc29 has been submitted as an update to Fedora 29. https://bodhi.fedoraproject.org/updates/FEDORA-2018-17cbc3c616
dnf-4.0.9-1.fc29, dnf-plugins-core-4.0.2-1.fc29, dnf-plugins-extras-4.0.0-1.fc29, libdnf-0.22.3-1.fc29 has been pushed to the Fedora 29 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2018-17cbc3c616
dnf-4.0.9-1.fc29, dnf-plugins-core-4.0.2-1.fc29, dnf-plugins-extras-4.0.0-1.fc29, libdnf-0.22.3-1.fc29 has been pushed to the Fedora 29 stable repository. If problems still persist, please make note of it in this bug report.