Re: Segmentation fault when trying to do a domain backup online

On 27.04.2026 17:18, Peter Milesson via samba wrote:
> Hi folks,
>
> I'm trying to do a domain backup online. Functional level and domain 
> level both 2016. OS Debian 13. Samba 4.23.6 from Trixie backports. The 
> whole conversation (redacted) is displayed below.
>
> If somebody could help me with this, I would be grateful.
>
> Best regards,
>
> Peter
>
> administrator@nuctest:~$ samba-tool domain backup online 
> --server=domsrv3.private.talps --targetdir=.
> INFO 2026-04-27 17:06:47,025 pid:73460 
> /usr/lib/python3/dist-packages/samba/join.py #1650: workgroup is PRIVATE
> INFO 2026-04-27 17:06:47,026 pid:73460 
> /usr/lib/python3/dist-packages/samba/join.py #1653: realm is 
> private.talps
> Calling bare provision
> INFO 2026-04-27 17:06:47,035 pid:73460 
> /usr/lib/python3/dist-packages/samba/provision/__init__.py #2112: 
> Looking up IPv4 addresses
> INFO 2026-04-27 17:06:47,036 pid:73460 
> /usr/lib/python3/dist-packages/samba/provision/__init__.py #2129: 
> Looking up IPv6 addresses
> WARNING 2026-04-27 17:06:47,036 pid:73460 
> /usr/lib/python3/dist-packages/samba/provision/__init__.py #2136: No 
> IPv6 address will be assigned
> INFO 2026-04-27 17:06:47,286 pid:73460 
> /usr/lib/python3/dist-packages/samba/provision/__init__.py #2302: 
> Setting up share.ldb
> INFO 2026-04-27 17:06:47,312 pid:73460 
> /usr/lib/python3/dist-packages/samba/provision/__init__.py #2306: 
> Setting up secrets.ldb
> INFO 2026-04-27 17:06:47,332 pid:73460 
> /usr/lib/python3/dist-packages/samba/provision/__init__.py #2311: 
> Setting up the registry
> INFO 2026-04-27 17:06:47,368 pid:73460 
> /usr/lib/python3/dist-packages/samba/provision/__init__.py #2314: 
> Setting up the privileges database
> INFO 2026-04-27 17:06:47,398 pid:73460 
> /usr/lib/python3/dist-packages/samba/provision/__init__.py #2317: 
> Setting up idmap db
> INFO 2026-04-27 17:06:47,429 pid:73460 
> /usr/lib/python3/dist-packages/samba/provision/__init__.py #2324: 
> Setting up SAM db
> INFO 2026-04-27 17:06:47,439 pid:73460 
> /usr/lib/python3/dist-packages/samba/provision/__init__.py #887: 
> Setting up sam.ldb partitions and settings
> INFO 2026-04-27 17:06:47,441 pid:73460 
> /usr/lib/python3/dist-packages/samba/provision/__init__.py #899: 
> Setting up sam.ldb rootDSE
> INFO 2026-04-27 17:06:47,450 pid:73460 
> /usr/lib/python3/dist-packages/samba/provision/__init__.py #1312: 
> Pre-loading the Samba 4 and AD schema
> Unable to determine the DomainSID, can not enforce uniqueness 
> constraint on local domainSIDs
>
> INFO 2026-04-27 17:06:47,486 pid:73460 
> /usr/lib/python3/dist-packages/samba/provision/__init__.py #2425: A 
> Kerberos configuration suitable for Samba AD has been generated at 
> /home/administrator/tmpmi8dxlwp/private/krb5.conf
> INFO 2026-04-27 17:06:47,486 pid:73460 
> /usr/lib/python3/dist-packages/samba/provision/__init__.py #2427: 
> Merge the contents of this file with your system krb5.conf or replace 
> it with this one. Do not create a symlink!
> Provision OK for domain DN DC=private,DC=talps
> INFO 2026-04-27 17:06:47,494 pid:73460 
> /usr/lib/python3/dist-packages/samba/join.py #973: Starting replication
> Using DS_BIND_GUID_W2K3
> Schema-DN[CN=Schema,CN=Configuration,DC=private,DC=talps] 
> objects[402/1783] linked_values[0/0]
> Schema-DN[CN=Schema,CN=Configuration,DC=private,DC=talps] 
> objects[804/1783] linked_values[0/0]
> Schema-DN[CN=Schema,CN=Configuration,DC=private,DC=talps] 
> objects[1206/1783] linked_values[0/0]
> Schema-DN[CN=Schema,CN=Configuration,DC=private,DC=talps] 
> objects[1599/1783] linked_values[0/0]
> Schema-DN[CN=Schema,CN=Configuration,DC=private,DC=talps] 
> objects[1783/1783] linked_values[0/0]
> Analyze and apply schema objects
> Partition[CN=Configuration,DC=private,DC=talps] objects[402/2904] 
> linked_values[0/74]
> Partition[CN=Configuration,DC=private,DC=talps] objects[804/2904] 
> linked_values[0/74]
> Partition[CN=Configuration,DC=private,DC=talps] objects[1206/2904] 
> linked_values[0/74]
> Partition[CN=Configuration,DC=private,DC=talps] objects[1608/2904] 
> linked_values[0/74]
> Partition[CN=Configuration,DC=private,DC=talps] objects[1924/2904] 
> linked_values[74/74]
> dsdb_replicated_objects_convert: Ignoring object outside partition 
> e6c65d1b-902a-412e-88b5-46a551de1d8b 
> CN=Schema,CN=Configuration,DC=private,DC=talps: 
> WERR_DS_ADD_REPLICA_INHIBITED
> Replicating critical objects from the base DN of the domain
> Partition[DC=private,DC=talps] objects[114/161] linked_values[10/120]
> Partition[DC=private,DC=talps] objects[304/3255] linked_values[123/120]
> ===============================================================
> INTERNAL ERROR: Signal 11: Segmentation fault in  () () pid 73460 
> (4.23.6-Debian-4.23.6+dfsg-2~bpo13+1)
> If you are running a recent Samba version, and if you think this 
> problem is not yet fixed in the latest versions, please consider 
> reporting this bug, see https://wiki.samba.org/index.php/Bug_Reporting
> ===============================================================
> PANIC (pid 73460): Signal 11: Segmentation fault in 
> 4.23.6-Debian-4.23.6+dfsg-2~bpo13+1
> BACKTRACE: 35 stack frames:
>  #0 
> /usr/lib/x86_64-linux-gnu/samba/libgenrand-private-samba.so.0(log_stack_trace+0x2d) 
> [0x7fcb547aa5bd]
>  #1 
> /usr/lib/x86_64-linux-gnu/samba/libgenrand-private-samba.so.0(smb_panic+0xd) 
> [0x7fcb547aa85d]
>  #2 
> /usr/lib/x86_64-linux-gnu/samba/libgenrand-private-samba.so.0(+0x28f5) 
> [0x7fcb547aa8f5]
>  #3 /lib/x86_64-linux-gnu/libc.so.6(+0x3fdf0) [0x7fcb55242df0]
>  #4 /usr/lib/x86_64-linux-gnu/samba/ldb/repl_meta_data.so(+0xa7c6) 
> [0x7fcb4d6c07c6]
>  #5 
> /usr/lib/x86_64-linux-gnu/samba/libldb-key-value-private-samba.so.0(+0x6eae) 
> [0x7fcb4d816eae]
>  #6 
> /lib/x86_64-linux-gnu/libtevent.so.0(tevent_common_invoke_timer_handler+0xef) 
> [0x7fcb54899fdf]
>  #7 
> /lib/x86_64-linux-gnu/libtevent.so.0(tevent_common_loop_timer_delay+0xb3) 
> [0x7fcb5489a203]
>  #8 /lib/x86_64-linux-gnu/libtevent.so.0(+0xf84b) [0x7fcb5489b84b]
>  #9 /lib/x86_64-linux-gnu/libtevent.so.0(+0xd54b) [0x7fcb5489954b]
>  #10 /lib/x86_64-linux-gnu/libtevent.so.0(_tevent_loop_once+0x93) 
> [0x7fcb548939c3]
>  #11 /lib/x86_64-linux-gnu/libldb.so.2(ldb_wait+0x9b) [0x7fcb548bcb2b]
>  #12 /lib/x86_64-linux-gnu/libldb.so.2(ldb_extended+0x118) 
> [0x7fcb548bdd68]
>  #13 
> /lib/x86_64-linux-gnu/libsamdb.so.0(dsdb_replicated_objects_commit+0x25f) 
> [0x7fcb4fe8864f]
>  #14 
> /usr/lib/x86_64-linux-gnu/samba/libsamba-net-join.cpython-313-x86-64-linux-gnu-private-samba.so.0(libnet_vampire_cb_store_chunk+0x5e9) 
> [0x7fcb4e2c5e39]
>  #15 
> /usr/lib/python3/dist-packages/samba/net.cpython-313-x86_64-linux-gnu.so(+0x4d8d) 
> [0x7fcb4e6b0d8d]
>  #16 /usr/bin/python3() [0x591ceb]
>  #17 /usr/bin/python3(PyObject_Vectorcall+0x32) [0x54cf22]
>  #18 /usr/bin/python3(_PyEval_EvalFrameDefault+0x95b7) [0x56acf7]
>  #19 /usr/bin/python3() [0x5cd43a]
>  #20 /usr/bin/python3() [0x5abce5]
>  #21 /usr/bin/python3(_PyEval_EvalFrameDefault+0x4008) [0x565748]
>  #22 /usr/bin/python3() [0x5cd3c9]
>  #23 /usr/bin/python3(_PyEval_EvalFrameDefault+0x4008) [0x565748]
>  #24 /usr/bin/python3(PyEval_EvalCode+0xcc) [0x55d48c]
>  #25 /usr/bin/python3() [0x6ab8d1]
>  #26 /usr/bin/python3() [0x6a899c]
>  #27 /usr/bin/python3() [0x6b9943]
>  #28 /usr/bin/python3() [0x6b93e3]
>  #29 /usr/bin/python3() [0x6b921e]
>  #30 /usr/bin/python3(Py_RunMain+0x3c1) [0x6b86f1]
>  #31 /usr/bin/python3(Py_BytesMain+0x2b) [0x6838eb]
>  #32 /lib/x86_64-linux-gnu/libc.so.6(+0x29ca8) [0x7fcb5522cca8]
>  #33 /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x85) 
> [0x7fcb5522cd65]
>  #34 /usr/bin/python3(_start+0x21) [0x682c81]
> Aborted
>
>
Hi folks,

I tried to do a domain backup using another DC as server, this one with 
Windows 2025 Server. This went through without problems. The DC where 
the domain backup failed has got the FSMO roles. But that should not 
matter, I assume. This successful backup is displayed below (redacted, 
incl. names).

I hope it helps to track down the problem.

Best regards,

Peter

administrator@appserver2:~$ samba-tool domain backup online 
--server=domsrv4.private.talps --targetdir=./backups
INFO 2026-04-27 18:43:40,479 pid:1869 
/usr/lib/python3/dist-packages/samba/join.py #1650: workgroup is private
INFO 2026-04-27 18:43:40,479 pid:1869 
/usr/lib/python3/dist-packages/samba/join.py #1653: realm is private.talps
Calling bare provision
INFO 2026-04-27 18:43:40,482 pid:1869 
/usr/lib/python3/dist-packages/samba/provision/__init__.py #2112: 
Looking up IPv4 addresses
INFO 2026-04-27 18:43:40,482 pid:1869 
/usr/lib/python3/dist-packages/samba/provision/__init__.py #2129: 
Looking up IPv6 addresses
WARNING 2026-04-27 18:43:40,482 pid:1869 
/usr/lib/python3/dist-packages/samba/provision/__init__.py #2136: No 
IPv6 address will be assigned
INFO 2026-04-27 18:43:40,557 pid:1869 
/usr/lib/python3/dist-packages/samba/provision/__init__.py #2302: 
Setting up share.ldb
INFO 2026-04-27 18:43:40,562 pid:1869 
/usr/lib/python3/dist-packages/samba/provision/__init__.py #2306: 
Setting up secrets.ldb
INFO 2026-04-27 18:43:40,566 pid:1869 
/usr/lib/python3/dist-packages/samba/provision/__init__.py #2311: 
Setting up the registry
INFO 2026-04-27 18:43:40,576 pid:1869 
/usr/lib/python3/dist-packages/samba/provision/__init__.py #2314: 
Setting up the privileges database
INFO 2026-04-27 18:43:40,582 pid:1869 
/usr/lib/python3/dist-packages/samba/provision/__init__.py #2317: 
Setting up idmap db
INFO 2026-04-27 18:43:40,587 pid:1869 
/usr/lib/python3/dist-packages/samba/provision/__init__.py #2324: 
Setting up SAM db
INFO 2026-04-27 18:43:40,588 pid:1869 
/usr/lib/python3/dist-packages/samba/provision/__init__.py #887: Setting 
up sam.ldb partitions and settings
INFO 2026-04-27 18:43:40,588 pid:1869 
/usr/lib/python3/dist-packages/samba/provision/__init__.py #899: Setting 
up sam.ldb rootDSE
INFO 2026-04-27 18:43:40,589 pid:1869 
/usr/lib/python3/dist-packages/samba/provision/__init__.py #1312: 
Pre-loading the Samba 4 and AD schema
Unable to determine the DomainSID, can not enforce uniqueness constraint 
on local domainSIDs

INFO 2026-04-27 18:43:40,595 pid:1869 
/usr/lib/python3/dist-packages/samba/provision/__init__.py #2425: A 
Kerberos configuration suitable for Samba AD has been generated at 
/home/administrator/backups/tmpcwxt810z/private/krb5.conf
INFO 2026-04-27 18:43:40,595 pid:1869 
/usr/lib/python3/dist-packages/samba/provision/__init__.py #2427: Merge 
the contents of this file with your system krb5.conf or replace it with 
this one. Do not create a symlink!
Provision OK for domain DN DC=private,DC=talps
INFO 2026-04-27 18:43:40,596 pid:1869 
/usr/lib/python3/dist-packages/samba/join.py #973: Starting replication
Using DS_BIND_GUID_W2K3
Schema-DN[CN=Schema,CN=Configuration,DC=private,DC=talps] 
objects[402/1473] linked_values[0/0]
Schema-DN[CN=Schema,CN=Configuration,DC=private,DC=talps] 
objects[804/1473] linked_values[0/0]
Schema-DN[CN=Schema,CN=Configuration,DC=private,DC=talps] 
objects[1206/1473] linked_values[0/0]
Schema-DN[CN=Schema,CN=Configuration,DC=private,DC=talps] 
objects[1599/1473] linked_values[0/0]
Schema-DN[CN=Schema,CN=Configuration,DC=private,DC=talps] 
objects[1783/1473] linked_values[0/0]
Analyze and apply schema objects
Partition[CN=Configuration,DC=private,DC=talps] objects[402/2129] 
linked_values[0/74]
Partition[CN=Configuration,DC=private,DC=talps] objects[804/2129] 
linked_values[0/74]
Partition[CN=Configuration,DC=private,DC=talps] objects[1206/2129] 
linked_values[0/74]
Partition[CN=Configuration,DC=private,DC=talps] objects[1608/2129] 
linked_values[0/74]
Partition[CN=Configuration,DC=private,DC=talps] objects[1924/2129] 
linked_values[74/74]
dsdb_replicated_objects_convert: Ignoring object outside partition 
e6c65d1b-902a-412e-88b5-46a551de1d8b 
CN=Schema,CN=Configuration,DC=private,DC=talps: 
WERR_DS_ADD_REPLICA_INHIBITED
Replicating critical objects from the base DN of the domain
Partition[DC=private,DC=talps] objects[114/161] linked_values[10/165]
Partition[DC=private,DC=talps] objects[308/2981] linked_values[75/165]
dsdb_replicated_objects_convert: Ignoring object outside partition 
3cc0bf24-521b-4524-8c77-8c57ae163790 
CN=Configuration,DC=private,DC=talps: WERR_DS_ADD_REPLICA_INHIBITED
Failed to commit objects: WERR_DS_DRA_RECYCLED_TARGET
Missing target object - retrying with DRS_GET_TGT
Partition[DC=private,DC=talps] objects[615/2981] linked_values[86/165]
dsdb_replicated_objects_convert: Ignoring object outside partition 
3cc0bf24-521b-4524-8c77-8c57ae163790 
CN=Configuration,DC=private,DC=talps: WERR_DS_ADD_REPLICA_INHIBITED
Partition[DC=private,DC=talps] objects[816/2981] linked_values[239/165]
dsdb_replicated_objects_convert: Ignoring object outside partition 
b730703c-3c08-43f3-8ee1-1e1dadb27b67 
DC=DomainDnsZones,DC=private,DC=talps: WERR_DS_ADD_REPLICA_INHIBITED
dsdb_replicated_objects_convert: Ignoring object outside partition 
e096b9a5-6e45-4a47-bfad-d8061bf9e442 
DC=ForestDnsZones,DC=private,DC=talps: WERR_DS_ADD_REPLICA_INHIBITED
Partition[DC=private,DC=talps] objects[909/2981] linked_values[239/165]
Done with always replicated NC (base, config, schema)
Replicating DC=DomainDnsZones,DC=private,DC=talps
Partition[DC=DomainDnsZones,DC=private,DC=talps] objects[42/313] 
linked_values[0/0]
Partition[DC=DomainDnsZones,DC=private,DC=talps] objects[318/313] 
linked_values[0/0]
Replicating DC=ForestDnsZones,DC=private,DC=talps
Partition[DC=ForestDnsZones,DC=private,DC=talps] objects[27/27] 
linked_values[0/0]
INFO 2026-04-27 18:43:42,120 pid:1869 
/usr/lib/python3/dist-packages/samba/join.py #1094: Committing SAM 
database - this may take some time
replmd_allow_missing_target: CN=Rulle 
Monster\0ADEL:e816ab47-cad4-4713-8463-830717e2525e,CN=Deleted 
Objects,DC=private,DC=talps is Deleted but up to date. Ignoring link 
from CN=MSOfficeUsers,CN=Users,DC=private,DC=talps
replmd_allow_missing_target: CN=Rulle 
Monster\0ADEL:e816ab47-cad4-4713-8463-830717e2525e,CN=Deleted 
Objects,DC=private,DC=talps is Deleted but up to date. Ignoring link 
from CN=Crap dept,CN=Users,DC=private,DC=talps
Repacking database from v1 to v2 format (first record 
CN=ms-SPP-Activation-Object,CN=Schema,CN=Configuration,DC=private,DC=talps)
Repack: re-packed 10000 records so far
Repacking database from v1 to v2 format (first record 
CN=nTDSSettings-Display,CN=C0A,CN=DisplaySpecifiers,CN=Configuration,DC=private,DC=talps)
Repacking database from v1 to v2 format (first record DC=Samsung 
phone-Mike\0ADEL:c3fd0028-50c5-4058-be31-8c5f6fb1ea78,CN=Deleted 
Objects,DC=DomainDnsZones,DC=private,DC=talps)
Repacking database from v1 to v2 format (first record 
CN=LostAndFound,DC=ForestDnsZones,DC=private,DC=talps)
Repacking database from v1 to v2 format (first record CN=Access Control 
Assistance Operators,CN=Builtin,DC=private,DC=talps)
INFO 2026-04-27 18:43:42,812 pid:1869 
/usr/lib/python3/dist-packages/samba/join.py #1114: Committed SAM database
INFO 2026-04-27 18:43:42,814 pid:1869 
/usr/lib/python3/dist-packages/samba/join.py #1692: Setting 
isSynchronized and dsServiceName
INFO 2026-04-27 18:43:42,816 pid:1869 
/usr/lib/python3/dist-packages/samba/join.py #1656: Cloned domain 
private (SID S-1-5-21-3841312322-1698605220-122548794)
INFO 2026-04-27 18:43:42,845 pid:1869 
/usr/lib/python3/dist-packages/samba/netcmd/domain/backup.py #290: 
Backing up sysvol files (via SMB)...
Password for [[email protected]]:
INFO 2026-04-27 18:44:06,011 pid:1869 
/usr/lib/python3/dist-packages/samba/netcmd/domain/backup.py #147: 
Creating backup file 
./backups/samba-backup-private.talps-2026-04-27T18-44-05.982281.tar.bz2...


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