Cash-flow report fails with exception

[Raphael Mankin]

I have had a cash-flow report configured and unchanged for several y ears. Lately it is failing.

Gnucash 3.8
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.04.3 LTS
Release: 20.04
Codename: focal

Report output and specification attached

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: gnucash 1:3.8b-1ubuntu1
ProcVersionSignature: Ubuntu 5.4.0-91.102-generic 5.4.151
Uname: Linux 5.4.0-91-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.21
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: XFCE
Date: Fri Dec 17 12:15:35 2021
InstallationDate: Installed on 2018-02-09 (1407 days ago)
InstallationMedia: Xubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
SourcePackage: gnucash
UpgradeStatus: Upgraded to focal on 2020-10-09 (434 days ago)

[Raphael Mankin (raph-p)]

Added the 2nd attachment as the original form only permitted one attachment.

[Raphael Mankin (raph-p)]

Still an issue: Version: 3.8
Build ID: 3.8b+(2019-12-29)
Finance::Quote: 1.49

Report error

An error occurred while running the report.

          18 (apply-smob/1 #<catch-closure 564a3cd35880>)
In c-interface.scm:
     22:4 17 (gnc:call-with-error-handling _ _)
In ice-9/boot-9.scm:
    829:9 16 (catch #t #<procedure 564a3d3eb270 at c-interface.scm:23:6 ()> # …)
In c-interface.scm:
    27:37 15 (_)
In unknown file:
          14 (eval-string "(gnc:report-run 2)" #<undefined>)
In ice-9/boot-9.scm:
   2312:4 13 (save-module-excursion #<procedure 564a3f821b00 at ice-9/eval-s…>)
In ice-9/eval-string.scm:
     38:6 12 (read-and-eval #<input: string 564a3d7443f0> #:lang _)
In report.scm:
    776:4 11 (gnc:report-run _)
In c-interface.scm:
    64:23 10 (gnc:backtrace-if-exception _ . _)
     22:4 9 (gnc:call-with-error-handling _ _)
In ice-9/boot-9.scm:
    829:9 8 (catch #t #<procedure 564a3d3eb1b0 at c-interface.scm:23:6 ()> # …)
In c-interface.scm:
    26:40 7 (_)
In report.scm:
   780:24 6 (_)
   756:25 5 (gnc:report-render-html #<<report> type: f8748b813fab4220ba26e…> …)
In cash-flow.scm:
   200:16 4 (cash-flow-renderer _)
In ice-9/boot-9.scm:
   222:17 3 (map1 (() #<swig-pointer Account * 564a3de1dcc0> #<swig-poin…> …))
In cash-flow.scm:
   210:21 2 (_ ())
In html-utilities.scm:
    35:35 1 (gnc:register-guid "acct-guid=" #f)
In unknown file:
           0 (string-append "acct-guid=" #f)

In procedure string-append: Wrong type (expecting string): #f