In some cases, mostly python packages that have optional support for python3 in the spec file but it's been disabled f-r wrongly evaluates which binary packages should be created and then fails with similar errors:
{{{
Traceback (most recent call last):
File "/home/w0rm/work/projects/fedora-review/src/FedoraReview/review_helper.py", line 194, in run
self._do_run()
File "/home/w0rm/work/projects/fedora-review/src/FedoraReview/review_helper.py", line 185, in _do_run
self.__do_report()
File "/home/w0rm/work/projects/fedora-review/src/FedoraReview/review_helper.py", line 81, in __do_report
self.__run_checks(self.bug.spec_file, self.bug.srpm_file)
File "/home/w0rm/work/projects/fedora-review/src/FedoraReview/review_helper.py", line 100, in __run_checks
writedown=not Settings.no_report)
File "/home/w0rm/work/projects/fedora-review/src/FedoraReview/checks.py", line 353, in run_checks
run_check(name)
File "/home/w0rm/work/projects/fedora-review/src/FedoraReview/checks.py", line 335, in run_check
check.run()
File "/home/w0rm/work/projects/fedora-review/src/FedoraReview/check_base.py", line 231, in run
if self.is_applicable():
File "/home/w0rm/work/projects/fedora-review/src/FedoraReview/check_base.py", line 221, in is_applicable
return self.registry.is_applicable()
File "/home/w0rm/work/projects/fedora-review/plugins/sugar_activity.py", line 33, in is_applicable
return self.checks.rpms.find(regex) != None
File "/home/w0rm/work/projects/fedora-review/src/FedoraReview/datasrc.py", line 85, in find
for f in self.get_filelist(s):
File "/home/w0rm/work/projects/fedora-review/src/FedoraReview/datasrc.py", line 205, in get_filelist
return self.rpms_by_pkg[container].filelist
File "/home/w0rm/work/projects/fedora-review/src/FedoraReview/rpm_file.py", line 138, in filelist
self.init()
File "/home/w0rm/work/projects/fedora-review/src/FedoraReview/rpm_file.py", line 73, in init
self.filename = Mock.get_package_rpm_path(self.name, self)
File "/home/w0rm/work/projects/fedora-review/src/FedoraReview/mock.py", line 134, in get_package_rpm_path
raise ReviewError('No built package found for ' + pkg_name)
ReviewError: 'No built package found for python3-smbc'
}}}

This mostly happens when reviewing prebuild rpms created on other system with different definitions (such as running review of EPEL rpms on Fedora system). For example python packages enable python3 subpackage on Fedora so rpm believes there is such subpackage when looking at the specfile, but these rpms will not be built in EPEL causing f-r to fail later.

If you do run f-r using EPEL buildroot the same failures can happen