reconfiguration failed after update from 18.0.2 to 18.1 with PG::UniqueViolation: ERROR

Summary

I tried to update my 18.0.2 install to GitLab 18.1 and ended up with DB migration errors.

Steps to reproduce

apt update && apt dist-upgrade

What is the current bug behavior?

Generated at 2025-06-19 21:23:08 +0200
Mixlib::ShellOut::ShellCommandFailed: rails_migration[gitlab-rails] (gitlab::database_migrations line 51) had an error: Mixlib::ShellOut::ShellCommandFailed: bash_hide_env[migrate gitlab-rails database] (gitlab::database_migrations line 20) had an error: Mixlib::ShellOut::ShellCommandFailed: Expected process to exit with [0], but received '1'
---- Begin output of "bash"  ----
STDOUT: rake aborted!
StandardError: An error has occurred, all later migrations canceled:

PG::UniqueViolation: ERROR:  could not create unique index "index_merge_request_diff_commit_users_on_org_id_name_email"
DETAIL:  Key (organization_id, name, email)=(1, Thomas Lüder, t.lueder@nets.de) is duplicated.

Relevant logs and/or screenshots

cinc-stacktrace.out

Results of GitLab environment info

Output after the restore to 18.0.2

Expand for output related to GitLab environment info

System information
System:         Ubuntu 24.04
Proxy:          no
Current User:   git
Using RVM:      no
Ruby Version:   3.2.5
Gem Version:    3.6.7
Bundler Version:2.6.5
Rake Version:   13.0.6
Redis Version:  7.2.7
Sidekiq Version:7.3.9
Go Version:     unknown

GitLab information
Version:        18.0.2-ee
Revision:       073fca15cf9
Directory:      /opt/gitlab/embedded/service/gitlab-rails
DB Adapter:     PostgreSQL
DB Version:     16.8
URL:            https://XXXXXXX.dev
HTTP Clone URL: https://XXXXXXX.dev/some-group/some-project.git
SSH Clone URL:  git@XXXXXXX.dev:some-group/some-project.git
Elasticsearch:  no
Geo:            no
Using LDAP:     no
Using Omniauth: yes
Omniauth Providers: google_oauth2

GitLab Shell
Version:        14.42.0
Repository storages:
- default:      unix:/var/opt/gitlab/gitaly/gitaly.socket
GitLab Shell path:              /opt/gitlab/embedded/service/gitlab-shell

Gitaly
- default Address:      unix:/var/opt/gitlab/gitaly/gitaly.socket
- default Version:      18.0.2
- default Git Version:  2.49.0.gl2
- 

Results of GitLab application Check

Output after the restore to 18.0.2

Expand for output related to the GitLab application check

Checking GitLab subtasks ...
Checking GitLab Shell ...
GitLab Shell: ... GitLab Shell version >= 14.42.0 ? ... OK (14.42.0)
Running /opt/gitlab/embedded/service/gitlab-shell/bin/gitlab-shell-check
Internal API available: OK
Redis available via internal API: OK
gitlab-shell self-check successful
Checking GitLab Shell ... Finished
Checking Gitaly ...
Gitaly: ... default ... OK
Checking Gitaly ... Finished
Checking Sidekiq ...
Sidekiq: ... Running? ... yes
Number of Sidekiq processes (cluster/worker) ... 1/1
Checking Sidekiq ... Finished
Checking Incoming Email ...
Incoming Email: ... Checking Reply by email ...
IMAP server credentials are correct? ... Checking servicedesk@XXXXXXX.dev
yes
Mailroom enabled? ... skipped
MailRoom running? ... skipped
Checking Reply by email ... Finished
Checking Incoming Email ... Finished
Checking LDAP ...
LDAP: ... LDAP is disabled in config/gitlab.yml
Checking LDAP ... Finished
Checking GitLab App ...
Database config exists? ... yes
Tables are truncated? ... skipped
All migrations up? ... yes
Database contains orphaned GroupMembers? ... no
GitLab config exists? ... yes
GitLab config up to date? ... yes
Cable config exists? ... yes
Resque config exists? ... yes
Log directory writable? ... yes
Tmp directory writable? ... yes
Uploads directory exists? ... yes
Uploads directory has correct permissions? ... yes
Uploads directory tmp has correct permissions? ... yes
Systemd unit files or init script exist? ... skipped (omnibus-gitlab has neither init script nor systemd units)
Systemd unit files or init script up-to-date? ... skipped (omnibus-gitlab has neither init script nor systemd units)
Projects have namespace: ...
3/1 ... yes
3/2 ... yes
6/3 ... yes
4/4 ... yes
4/5 ... yes
7/6 ... yes
4/7 ... yes
4/8 ... yes
4/9 ... yes
5/10 ... yes
8/11 ... yes
8/12 ... yes
9/13 ... yes
10/14 ... yes
11/15 ... yes
11/16 ... yes
12/17 ... yes
12/18 ... yes
13/19 ... yes
14/20 ... yes
15/21 ... yes
15/22 ... yes
15/23 ... yes
15/24 ... yes
15/25 ... yes
15/26 ... yes
16/27 ... yes
16/28 ... yes
16/29 ... yes
16/30 ... yes
16/31 ... yes
17/32 ... yes
17/33 ... yes
17/34 ... yes
18/35 ... yes
19/36 ... yes
19/37 ... yes
19/38 ... yes
19/39 ... yes
20/40 ... yes
21/41 ... yes
22/42 ... yes
23/43 ... yes
24/44 ... yes
26/45 ... yes
25/46 ... yes
25/47 ... yes
25/48 ... yes
25/49 ... yes
25/50 ... yes
25/51 ... yes
25/52 ... yes
25/53 ... yes
25/54 ... yes
25/55 ... yes
27/56 ... yes
27/57 ... yes
28/58 ... yes
28/59 ... yes
28/60 ... yes
28/61 ... yes
28/62 ... yes
29/63 ... yes
30/64 ... yes
32/65 ... yes
32/66 ... yes
32/67 ... yes
32/68 ... yes
32/69 ... yes
32/70 ... yes
31/71 ... yes
33/72 ... yes
33/73 ... yes
33/74 ... yes
33/75 ... yes
33/76 ... yes
33/77 ... yes
33/78 ... yes
33/79 ... yes
33/80 ... yes
34/81 ... yes
35/82 ... yes
36/83 ... yes
36/84 ... yes
36/85 ... yes
37/86 ... yes
37/87 ... yes
37/88 ... yes
38/89 ... yes
38/90 ... yes
38/91 ... yes
38/92 ... yes
38/93 ... yes
38/94 ... yes
40/95 ... yes
40/96 ... yes
40/97 ... yes
39/98 ... yes
39/99 ... yes
41/100 ... yes
42/102 ... yes
162/103 ... yes
162/104 ... yes
42/105 ... yes
42/106 ... yes
42/107 ... yes
42/108 ... yes
42/109 ... yes
162/110 ... yes
42/111 ... yes
42/112 ... yes
42/113 ... yes
42/114 ... yes
42/115 ... yes
42/116 ... yes
42/117 ... yes
42/118 ... yes
42/119 ... yes
44/120 ... yes
44/121 ... yes
44/122 ... yes
162/123 ... yes
162/124 ... yes
162/125 ... yes
162/126 ... yes
162/127 ... yes
162/128 ... yes
162/129 ... yes
162/130 ... yes
162/131 ... yes
162/132 ... yes
162/134 ... yes
162/135 ... yes
162/136 ... yes
162/137 ... yes
162/138 ... yes
162/141 ... yes
162/142 ... yes
162/143 ... yes
162/145 ... yes
162/146 ... yes
162/147 ... yes
162/148 ... yes
162/149 ... yes
162/150 ... yes
163/151 ... yes
163/152 ... yes
164/153 ... yes
164/154 ... yes
165/155 ... yes
166/156 ... yes
171/157 ... yes
171/158 ... yes
171/159 ... yes
171/160 ... yes
171/161 ... yes
171/162 ... yes
172/163 ... yes
173/164 ... yes
173/165 ... yes
173/166 ... yes
173/167 ... yes
173/168 ... yes
173/169 ... yes
173/170 ... yes
239/173 ... yes
226/174 ... yes
2/175 ... yes
2/176 ... yes
162/177 ... yes
42/178 ... yes
260/181 ... yes
266/183 ... yes
33/184 ... yes
267/185 ... yes
173/186 ... yes
42/187 ... yes
272/188 ... yes
42/189 ... yes
162/190 ... yes
162/191 ... yes
277/192 ... yes
277/193 ... yes
42/194 ... yes
277/195 ... yes
171/196 ... yes
277/197 ... yes
162/198 ... yes
25/199 ... yes
291/201 ... yes
171/202 ... yes
291/203 ... yes
291/204 ... yes
291/205 ... yes
301/207 ... yes
303/208 ... yes
304/209 ... yes
21/210 ... yes
317/211 ... yes
303/212 ... yes
303/213 ... yes
301/214 ... yes
2/215 ... yes
328/216 ... yes
304/218 ... yes
303/219 ... yes
303/220 ... yes
303/223 ... yes
303/224 ... yes
320/225 ... yes
304/226 ... yes
13/227 ... yes
342/228 ... yes
342/229 ... yes
342/230 ... yes
303/231 ... yes
4/232 ... yes
328/233 ... yes
2/236 ... yes
1/237 ... yes
171/238 ... yes
303/239 ... yes
303/240 ... yes
319/241 ... yes
Redis version >= 6.2.14? ... yes
Ruby version >= 3.0.6 ? ... yes (3.2.5)
Git user has default SSH configuration? ... yes
Active users: ... 39
Is authorized keys file accessible? ... yes
GitLab configured to store new projects in hashed storage? ... yes
All projects are in hashed storage? ... yes
Elasticsearch version 7.x-8.x or OpenSearch version 1.x ... skipped (Advanced Search is disabled)
All migrations must be finished before doing a major upgrade ... skipped (Advanced Search is disabled)
Checking GitLab App ... Finished
Checking GitLab subtasks ... Finished

Same problems during restore

While restoring 18.0.2 and importing the backup DB that was created just before the update I encountered some other kind of same issues.

2025-06-19 20:09:23 UTC -- ------ BEGIN ERRORS -----

2025-06-19 20:09:23 UTC -- ERROR:  could not create unique index "index_ci_refs_on_project_id_and_ref_path"
DETAIL:  Key (project_id, ref_path)=(136, refs/heads/change/bordabc) is duplicated.
ERROR:  could not create unique index "index_merge_request_diff_commit_users_on_name_and_email"
DETAIL:  Key (name, email)=(Thomas Lüder, t.lueder@nets.de) is duplicated.
ERROR:  could not create unique index "index_programming_languages_on_name"
DETAIL:  Key (name)=(HTML) is duplicated.
ERROR:  could not create unique index "index_software_licenses_on_unique_name"
DETAIL:  Key (name)=(BSD with attribution) is duplicated.

2025-06-19 20:09:23 UTC -- ------ END ERRORS -------

I've deleted the create index from the DB dump and was able to import it.

But how is this possible, that I can't restore a DB dump that was just created from the same postgresql version?