Returning ipp client-error-not-possible for create-job

I'm trying to update the cups package for openSUSE to 2.3.3op2.

In addition to changing upstream, I've also decided to run make check and make test during the build process (rpm %check section), 2.3.3op2 manages to compile and check on all targets (SLES 12.5 upto Factory), but the testsuite fails on SLE15.2, Leap 15.1 and Factory zSystems with FAIL: 34 error messages, expected 33.

[  417s] Test Summary
[  417s] 
[  417s] PASS: cupsd exited with no errors.
[  417s] PASS: All job control files purged.
[  417s] PASS: Printer 'Test1' correctly produced 37 page(s).
[  417s] PASS: Printer 'Test2' correctly produced 23 page(s).
[  417s] PASS: Printer 'Test3' correctly produced 2 page(s).
[  417s] PASS: 165 requests logged.
[  417s] PASS: CUPS-Get-Default not logged.
[  417s] PASS: 0 emergency messages.
[  417s] PASS: 0 alert messages.
[  417s] PASS: 0 critical messages.
[  417s] FAIL: 34 error messages, expected 33.
[  417s] E [19/Mar/2021:12:04:54.950854 +0000] [Client 2] Returning IPP client-error-bad-request for Get-Jobs (no URI) from localhost.
[  417s] E [19/Mar/2021:12:04:54.953741 +0000] Missing attributes-natural-language attribute.
[  417s] E [19/Mar/2021:12:04:54.953759 +0000] Missing printer-uri, job-uri, or ppd-name attribute.
[  417s] E [19/Mar/2021:12:04:54.953821 +0000] [Client 2] Returning IPP client-error-bad-request for Get-Jobs (no URI) from localhost.
[  417s] E [19/Mar/2021:12:04:54.956154 +0000] Missing attributes-charset attribute.
[  417s] E [19/Mar/2021:12:04:54.956172 +0000] Missing attributes-natural-language attribute.
[  417s] E [19/Mar/2021:12:04:54.956188 +0000] Missing printer-uri, job-uri, or ppd-name attribute.
[  417s] E [19/Mar/2021:12:04:54.956229 +0000] [Client 2] Returning IPP client-error-bad-request for Get-Jobs (no URI) from localhost.
[  417s] E [19/Mar/2021:12:04:54.957767 +0000] Missing attributes-charset attribute.
[  417s] E [19/Mar/2021:12:04:54.957785 +0000] Missing attributes-natural-language attribute.
[  417s] E [19/Mar/2021:12:04:54.957800 +0000] Missing printer-uri, job-uri, or ppd-name attribute.
[  417s] E [19/Mar/2021:12:04:54.957878 +0000] [Client 2] Returning IPP client-error-bad-request for Get-Jobs (no URI) from localhost.
[  417s] E [19/Mar/2021:12:04:54.958804 +0000] Missing printer-uri, job-uri, or ppd-name attribute.
[  417s] E [19/Mar/2021:12:04:54.958853 +0000] [Client 2] Returning IPP client-error-bad-request for Get-Jobs (no URI) from localhost.
[  418s] E [19/Mar/2021:12:04:54.960897 +0000] [Client 2] Returning IPP client-error-bad-request for Get-Jobs (ipp://localhost:8631/jobs) from localhost.
[  418s] E [19/Mar/2021:12:04:54.961922 +0000] [Client 2] Returning IPP server-error-version-not-supported for Get-Jobs (no URI) from localhost.
[  418s] E [19/Mar/2021:12:04:55.203118 +0000] [Client 4] Returning IPP client-error-bad-request for Print-Job (ipp://localhost:8631/printers/Test1) from localhost.
[  418s] E [19/Mar/2021:12:05:02.442505 +0000] [Client 5] Returning IPP client-error-too-many-subscriptions for Create-Printer-Subscriptions (ipp://localhost:8631/printers/Test1) from localhost.
[  418s] E [19/Mar/2021:12:05:02.458837 +0000] [Client 8] Returning IPP client-error-bad-request for Get-Printer-Attributes (no URI) from localhost.
[  418s] E [19/Mar/2021:12:05:02.477194 +0000] [Client 8] Returning IPP client-error-bad-request for Get-Printer-Attributes (no URI) from localhost.
[  418s] E [19/Mar/2021:12:05:02.478330 +0000] Missing attributes-natural-language attribute.
[  418s] E [19/Mar/2021:12:05:02.478388 +0000] [Client 8] Returning IPP client-error-bad-request for Get-Printer-Attributes (ipp://localhost:8631/printers/Test1) from localhost.
[  418s] E [19/Mar/2021:12:05:02.479305 +0000] Missing attributes-charset attribute.
[  418s] E [19/Mar/2021:12:05:02.479350 +0000] Missing attributes-natural-language attribute.
[  418s] E [19/Mar/2021:12:05:02.479401 +0000] [Client 8] Returning IPP client-error-bad-request for Get-Printer-Attributes (ipp://localhost:8631/printers/Test1) from localhost.
[  418s] E [19/Mar/2021:12:05:02.480708 +0000] Missing attributes-charset attribute.
[  418s] E [19/Mar/2021:12:05:02.480728 +0000] Missing attributes-natural-language attribute.
[  418s] E [19/Mar/2021:12:05:02.480785 +0000] [Client 8] Returning IPP client-error-bad-request for Get-Printer-Attributes (ipp://localhost:8631/printers/Test1) from localhost.
[  418s] E [19/Mar/2021:12:05:02.511870 +0000] [Client 8] Returning IPP server-error-version-not-supported for Get-Printer-Attributes (no URI) from localhost.
[  418s] E [19/Mar/2021:12:05:02.514085 +0000] Missing printer-uri, job-uri, or ppd-name attribute.
[  418s] E [19/Mar/2021:12:05:02.514177 +0000] [Client 8] Returning IPP client-error-bad-request for Get-Printer-Attributes (no URI) from localhost.
[  418s] E [19/Mar/2021:12:05:02.590432 +0000] [Client 8] Returning IPP client-error-not-possible for Cancel-Job (ipp://localhost:8631/printers/Test1) from localhost.
[  418s] E [19/Mar/2021:12:05:02.609595 +0000] [Client 8] Returning IPP client-error-not-possible for Cancel-Job (ipp://localhost:8631/printers/Test1) from localhost.
[  418s] E [19/Mar/2021:12:05:02.646590 +0000] [Client 8] Returning IPP client-error-bad-request for Send-Document (ipp://localhost:8631/printers/Test1) from localhost.
[  418s] PASS: 8 warning messages.
[  418s] PASS: 0 notice messages.
[  418s] PASS: 784 info messages.
[  418s] PASS: 23560 debug messages.
[  418s] PASS: 88718 debug2 messages.
[  418s] 
[  418s] Copied log file "access_log-2021-03-19-abuild" to test directory.
[  418s] Copied log file "debug_log-2021-03-19-abuild" to test directory.
[  418s] Copied log file "error_log-2021-03-19-abuild" to test directory.
[  418s] Copied log file "page_log-2021-03-19-abuild" to test directory.
[  418s] Copied report file "cups-str-2021-03-19-abuild.html" to test directory.
[  418s] 
[  418s] 1 tests failed.
[  418s] make: *** [Makefile:241: test] Error 1
[  418s] error: Bad exit status from /var/tmp/rpm-tmp.iN0zmj (%check)

The full log is here: home:sp1rit:branches:Printing/cups