We tried to send a request to the provided URL but an error occurred: undefined method `execute' for nil:NilClass`

Summary

When I hit "test settings" under Jenkins CI (not the deprecated one) I get a message on screen:

We tried to send a request to the provided URL but an error occurred: undefined method execute' for nil:NilClass

Steps to reproduce

Click "Test settings" under Jenkins CI

Expected behavior

Success message, or not a stack trace.

Actual behavior

Stack trace

Relevant logs and/or screenshots

No relevant logs in /home/git/gitlab/logs/*.log

Output of checks

Results of GitLab application Check

Checking GitLab Shell ...

GitLab Shell version >= 4.0.0 ? ... OK (4.0.0)
Repo base directory exists?
default... yes
Repo storage directories are symlinks?
default... no
Repo paths owned by git:git?
default... yes
Repo paths access is drwxrws---?
default... yes
hooks directories in repos are links: ... 
11/21 ... ok
17/24 ... ok
17/25 ... ok
11/26 ... ok
11/27 ... ok
1/28 ... ok
11/29 ... ok
17/30 ... ok
11/32 ... ok
17/33 ... ok
11/34 ... ok
11/35 ... ok
17/36 ... ok
17/38 ... ok
14/39 ... ok
14/40 ... ok
3/41 ... ok
14/42 ... ok
14/44 ... ok
14/45 ... ok
14/46 ... ok
14/47 ... ok
14/49 ... ok
14/51 ... ok
14/52 ... ok
16/53 ... ok
16/54 ... ok
16/55 ... ok
14/56 ... ok
14/58 ... ok
16/59 ... ok
17/60 ... ok
17/61 ... ok
14/63 ... ok
14/64 ... ok
14/65 ... ok
14/66 ... ok
14/67 ... ok
14/68 ... ok
14/69 ... ok
14/70 ... ok
14/72 ... ok
14/73 ... ok
14/74 ... ok
14/75 ... ok
16/77 ... ok
14/78 ... ok
1/79 ... ok
14/80 ... ok
14/81 ... ok
14/83 ... ok
14/84 ... ok
14/85 ... ok
14/87 ... ok
17/88 ... ok
17/89 ... ok
17/91 ... ok
14/93 ... ok
14/95 ... ok
1/96 ... ok
1/97 ... ok
17/98 ... ok
14/100 ... ok
14/101 ... ok
14/102 ... ok
14/103 ... ok
14/104 ... ok
14/106 ... ok
1/107 ... ok
14/110 ... ok
14/111 ... ok
17/112 ... ok
3/113 ... ok
17/114 ... ok
41/115 ... ok
14/116 ... ok
14/117 ... ok
14/118 ... ok
14/120 ... ok
14/121 ... ok
14/122 ... ok
3/123 ... ok
17/124 ... ok
3/125 ... ok
3/126 ... ok
3/127 ... ok
14/129 ... ok
14/130 ... ok
14/131 ... ok
17/132 ... ok
14/133 ... ok
3/134 ... ok
14/135 ... ok
14/136 ... ok
14/137 ... ok
14/138 ... ok
Running /home/git/gitlab-shell/bin/check
Check GitLab API access: OK
Access to /home/git/.ssh/authorized_keys: OK
Send ping to redis server: OK
gitlab-shell self-check successful

Checking GitLab Shell ... Finished

Checking Sidekiq ...

Running? ... yes
Number of Sidekiq processes ... 1

Checking Sidekiq ... Finished

Checking Reply by email ...

Reply by email is disabled in config/gitlab.yml

Checking Reply by email ... Finished

Checking LDAP ...

LDAP is disabled in config/gitlab.yml

Checking LDAP ... Finished

Checking GitLab ...

Git configured with autocrlf=input? ... yes
Database config exists? ... yes
All migrations up? ... yes
Database contains orphaned GroupMembers? ... no
GitLab config exists? ... yes
GitLab config outdated? ... no
Log directory writable? ... yes
Tmp directory writable? ... yes
Uploads directory setup correctly? ... yes
Init script exists? ... yes
Init script up-to-date? ... yes
projects have namespace: ... 
11/21 ... yes
17/24 ... yes
17/25 ... yes
11/26 ... yes
11/27 ... yes
1/28 ... yes
11/29 ... yes
17/30 ... yes
11/32 ... yes
17/33 ... yes
11/34 ... yes
11/35 ... yes
17/36 ... yes
17/38 ... yes
14/39 ... yes
14/40 ... yes
3/41 ... yes
14/42 ... yes
14/44 ... yes
14/45 ... yes
14/46 ... yes
14/47 ... yes
14/49 ... yes
14/51 ... yes
14/52 ... yes
16/53 ... yes
16/54 ... yes
16/55 ... yes
14/56 ... yes
14/58 ... yes
16/59 ... yes
17/60 ... yes
17/61 ... yes
14/63 ... yes
14/64 ... yes
14/65 ... yes
14/66 ... yes
14/67 ... yes
14/68 ... yes
14/69 ... yes
14/70 ... yes
14/72 ... yes
14/73 ... yes
14/74 ... yes
14/75 ... yes
16/77 ... yes
14/78 ... yes
1/79 ... yes
14/80 ... yes
14/81 ... yes
14/83 ... yes
14/84 ... yes
14/85 ... yes
14/87 ... yes
17/88 ... yes
17/89 ... yes
17/91 ... yes
14/93 ... yes
14/95 ... yes
1/96 ... yes
1/97 ... yes
17/98 ... yes
14/100 ... yes
14/101 ... yes
14/102 ... yes
14/103 ... yes
14/104 ... yes
14/106 ... yes
1/107 ... yes
14/110 ... yes
14/111 ... yes
17/112 ... yes
3/113 ... yes
17/114 ... yes
41/115 ... yes
14/116 ... yes
14/117 ... yes
14/118 ... yes
14/120 ... yes
14/121 ... yes
14/122 ... yes
3/123 ... yes
17/124 ... yes
3/125 ... yes
3/126 ... yes
3/127 ... yes
14/129 ... yes
14/130 ... yes
14/131 ... yes
17/132 ... yes
14/133 ... yes
3/134 ... yes
14/135 ... yes
14/136 ... yes
14/137 ... yes
14/138 ... yes
Redis version >= 2.8.0? ... yes
Ruby version >= 2.1.0 ? ... yes (2.3.0)
Your git bin path is "/usr/bin/git"
Git version >= 2.7.3 ? ... yes (2.10.2)
Active users: 13
Elasticsearch version 2.4.x? ... yes (2.4.0)
Elasticsearch has plugin delete-by-query installed? ... yes

Checking GitLab ... Finished

Results of GitLab environment info

System information
System:         Debian 7.11
Current User:   git
Using RVM:      no
Ruby Version:   2.3.0p0
Gem Version:
Bundler Version:1.7.6
Rake Version:   10.5.0
Sidekiq Version:4.2.1

GitLab information
Version:        8.14.0-ee
Revision:       e45e0d4
Directory:      /home/git/gitlab
DB Adapter:     Mysql2
DB Version:     5.5.52-0+deb7u1
URL:            https://git.dlcdev.com
HTTP Clone URL: https://git.dlcdev.com/some-group/some-project.git
SSH Clone URL:  git@git.dlcdev.com:some-group/some-project.git
Elasticsearch:  yes
Geo:            no
Using LDAP:     no
Using Omniauth: yes
Omniauth Providers: google_oauth2

GitLab Shell
Version:        4.0.0
Repository storage paths:
- default:      /home/git/repositories/
Hooks:          /home/git/gitlab-shell/hooks/
Git:            /usr/bin/git

Possible fixes

I think CE has the same issue, but I thought it didn't have the Jenkins service: https://gitlab.com/gitlab-org/gitlab-ce/issues/24778 Similar issue for the deprecated service: https://gitlab.com/gitlab-org/gitlab-ce/issues/18752