After transition from python 2.7 to 3.7, flow-report(1) seems to have some issues... for example:

# flow-cat ft-v05.2020-06-19.000001+0200 | flow-report 
Traceback (most recent call last):
  File "/usr/local/bin/flow-rptfmt", line 533, in <module>
    rpt.load(sys.stdin, opt_sort_field, opt_max_lines, opt_percent)
  File "/usr/local/bin/flow-rptfmt", line 297, in load
    splt = string.split(line2,',')
AttributeError: module 'string' has no attribute 'split'
flow-report: pclose(flow-rptfmt -f ascii): failed exit code=1.

Another example:

# flow-cat ft-v05.2020-06-19.000001+0200 | flow-report -v TYPE=ip-destination-address/ip-destination-port -v SORT=+octets -v OPTIONS=-header
Traceback (most recent call last):
  File "/usr/local/bin/flow-rptfmt", line 533, in <module>
    rpt.load(sys.stdin, opt_sort_field, opt_max_lines, opt_percent)
  File "/usr/local/bin/flow-rptfmt", line 324, in load
    for i in string.split(line[8:],','):
AttributeError: module 'string' has no attribute 'split'
flow-report: pclose(flow-rptfmt -f ascii): failed exit code=1.


As asked in bug #249388, comment #6, here is the content of /usr/local/etc/cfg/stat.cfg:

stat-report default
  type @{TYPE:-summary-detail}
  output
    format ascii
    sort @{SORT:-+}
    fields @{FIELDS:-+}
    options @{OPTIONS:-+header,+xheader,+totals}
    path |flow-rptfmt @{RPTOPT:--f ascii}

stat-definition default
  report default