Error 500 on route "/admin/application_settings/services/1882/edit" -> edit Prometheus Service Template

Summary

When going to Admin -> Service Templates and clicking on Prometheus Service Template, error 500 is the result and no page shows up.

Steps to reproduce

See above.

Example Project

What is the current bug behavior?

see above

What is the expected correct behavior?

I would expect to see the page to configure prometheus service template

Relevant logs and/or screenshots

Output of checks

Self-hosted Gitlab-CE

Results of GitLab environment info

Expand for output related to GitLab environment info

System information
System:         Ubuntu 16.04
Current User:   git
Using RVM:      no
Ruby Version:   2.3.6p384
Gem Version:    2.6.13
Bundler Version:1.13.7
Rake Version:   12.3.0
Redis Version:  3.2.11
Git Version:    2.14.3
Sidekiq Version:5.0.5
Go Version:     unknown
GitLab information
Version:        10.5.0
Revision:       34d5766
Directory:      /opt/gitlab/embedded/service/gitlab-rails
DB Adapter:     postgresql
URL:            https://sub.host.tld
HTTP Clone URL: https://sub.host.tld/some-group/some-project.git
SSH Clone URL:  git@sub.host.tld:some-group/some-project.git
Using LDAP:     no
Using Omniauth: yes
Omniauth Providers: github
GitLab Shell
Version:        6.0.3
Repository storage paths:

• default: /var/opt/gitlab/git-data/repositories Hooks: /opt/gitlab/embedded/service/gitlab-shell/hooks Git: /opt/gitlab/embedded/bin/git

Results of GitLab application Check

Expand for output related to the GitLab application check

Checking GitLab Shell ...
GitLab Shell version >= 6.0.3 ? ... OK (6.0.3)
Repo base directory exists?
default... yes
Repo storage directories are symlinks?
default... no
Repo paths owned by git:root, or git:git?
default... yes
Repo paths access is drwxrws---?
default... yes
hooks directories in repos are links: ...
2/3 ... ok
2/4 ... ok
3/6 ... ok
17/7 ... ok
17/8 ... ok
2/9 ... ok
17/10 ... ok
2/11 ... ok
3/12 ... ok
2/13 ... ok
2/14 ... ok
2/15 ... ok
2/16 ... ok
2/17 ... ok
2/18 ... ok
3/19 ... ok
54/20 ... ok
2/21 ... ok
3/22 ... ok
54/25 ... ok
8/26 ... ok
19/27 ... ok
19/28 ... ok
19/29 ... ok
31/30 ... ok
17/31 ... ok
31/32 ... ok
10/33 ... ok
31/34 ... ok
3/35 ... ok
3/36 ... ok
1/37 ... ok
32/38 ... ok
32/39 ... ok
1/40 ... ok
32/41 ... ok
17/42 ... ok
17/43 ... ok
3/44 ... ok
36/46 ... ok
17/48 ... ok
54/51 ... ok
26/52 ... repository is empty
27/57 ... ok
27/58 ... ok
27/60 ... ok
27/61 ... ok
28/63 ... ok
28/64 ... ok
28/66 ... ok
28/69 ... ok
29/70 ... ok
28/72 ... ok
45/73 ... ok
45/74 ... ok
2/75 ... ok
28/76 ... ok
29/77 ... ok
10/78 ... ok
17/79 ... ok
10/80 ... ok
3/81 ... ok
52/82 ... ok
10/83 ... ok
36/84 ... ok
30/85 ... ok
26/86 ... ok
34/90 ... ok
45/91 ... ok
9/92 ... ok
10/95 ... repository is empty
36/96 ... ok
32/97 ... ok
10/98 ... ok
19/99 ... ok
36/100 ... ok
3/101 ... ok
3/102 ... ok
17/103 ... ok
36/106 ... ok
17/110 ... ok
48/111 ... ok
17/112 ... ok
48/114 ... ok
16/115 ... ok
29/116 ... ok
3/117 ... ok
9/118 ... ok
26/119 ... ok
16/120 ... ok
25/121 ... ok
13/122 ... ok
24/123 ... ok
8/124 ... repository is empty
25/126 ... ok
25/127 ... ok
26/128 ... ok
45/129 ... ok
54/130 ... ok
17/131 ... ok
17/132 ... ok
31/133 ... ok
34/135 ... ok
31/137 ... ok
10/138 ... ok
10/139 ... ok
17/140 ... ok
27/141 ... ok
10/142 ... repository is empty
48/143 ... ok
29/144 ... ok
10/145 ... ok
17/146 ... ok
28/148 ... ok
10/149 ... ok
10/150 ... ok
1/151 ... ok
41/152 ... ok
17/153 ... ok
10/155 ... ok
17/156 ... ok
3/157 ... ok
48/158 ... ok
17/160 ... ok
17/161 ... ok
10/162 ... ok
17/163 ... ok
17/164 ... ok
28/165 ... ok
48/166 ... ok
26/167 ... ok
17/168 ... ok
28/169 ... ok
26/171 ... ok
26/172 ... ok
17/173 ... ok
45/174 ... ok
45/175 ... ok
45/176 ... ok
45/177 ... ok
2/179 ... repository is empty
54/180 ... ok
17/181 ... ok
17/182 ... ok
24/183 ... ok
54/185 ... ok
48/186 ... ok
48/187 ... repository is empty
3/188 ... ok
36/189 ... ok
28/190 ... repository is empty
Running /opt/gitlab/embedded/service/gitlab-shell/bin/check
Check GitLab API access: OK
Redis available via internal API: OK
Access to /var/opt/gitlab/.ssh/authorized_keys: OK
gitlab-shell self-check successful
Checking GitLab Shell ... Finished
Checking Sidekiq ...
Running? ... yes
Number of Sidekiq processes ... 1
Checking Sidekiq ... Finished
Reply by email is disabled in config/gitlab.yml
Checking LDAP ...
LDAP is disabled in config/gitlab.yml
Checking LDAP ... Finished
Checking GitLab ...
Git configured correctly? ... yes
Database config exists? ... yes
All migrations up? ... yes
Database contains orphaned GroupMembers? ... no
GitLab config exists? ... yes
GitLab config up to date? ... 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
Init script exists? ... skipped (omnibus-gitlab has no init script)
Init script up-to-date? ... skipped (omnibus-gitlab has no init script)
Projects have namespace: ...
2/3 ... yes
2/4 ... yes
3/6 ... yes
17/7 ... yes
17/8 ... yes
2/9 ... yes
17/10 ... yes
2/11 ... yes
3/12 ... yes
2/13 ... yes
2/14 ... yes
2/15 ... yes
2/16 ... yes
2/17 ... yes
2/18 ... yes
3/19 ... yes
54/20 ... yes
2/21 ... yes
3/22 ... yes
54/25 ... yes
8/26 ... yes
19/27 ... yes
19/28 ... yes
19/29 ... yes
31/30 ... yes
17/31 ... yes
31/32 ... yes
10/33 ... yes
31/34 ... yes
3/35 ... yes
3/36 ... yes
1/37 ... yes
32/38 ... yes
32/39 ... yes
1/40 ... yes
32/41 ... yes
17/42 ... yes
17/43 ... yes
3/44 ... yes
36/46 ... yes
17/48 ... yes
54/51 ... yes
26/52 ... yes
27/57 ... yes
27/58 ... yes
27/60 ... yes
27/61 ... yes
28/63 ... yes
28/64 ... yes
28/66 ... yes
28/69 ... yes
29/70 ... yes
28/72 ... yes
45/73 ... yes
45/74 ... yes
2/75 ... yes
28/76 ... yes
29/77 ... yes
10/78 ... yes
17/79 ... yes
10/80 ... yes
3/81 ... yes
52/82 ... yes
10/83 ... yes
36/84 ... yes
30/85 ... yes
26/86 ... yes
34/90 ... yes
45/91 ... yes
9/92 ... yes
10/95 ... yes
36/96 ... yes
32/97 ... yes
10/98 ... yes
19/99 ... yes
36/100 ... yes
3/101 ... yes
3/102 ... yes
17/103 ... yes
36/106 ... yes
17/110 ... yes
48/111 ... yes
17/112 ... yes
48/114 ... yes
16/115 ... yes
29/116 ... yes
3/117 ... yes
9/118 ... yes
26/119 ... yes
16/120 ... yes
25/121 ... yes
13/122 ... yes
24/123 ... yes
8/124 ... yes
25/126 ... yes
25/127 ... yes
26/128 ... yes
45/129 ... yes
54/130 ... yes
17/131 ... yes
17/132 ... yes
31/133 ... yes
34/135 ... yes
31/137 ... yes
10/138 ... yes
10/139 ... yes
17/140 ... yes
27/141 ... yes
10/142 ... yes
48/143 ... yes
29/144 ... yes
10/145 ... yes
17/146 ... yes
28/148 ... yes
10/149 ... yes
10/150 ... yes
1/151 ... yes
41/152 ... yes
17/153 ... yes
10/155 ... yes
17/156 ... yes
3/157 ... yes
48/158 ... yes
17/160 ... yes
17/161 ... yes
10/162 ... yes
17/163 ... yes
17/164 ... yes
28/165 ... yes
48/166 ... yes
26/167 ... yes
17/168 ... yes
28/169 ... yes
26/171 ... yes
26/172 ... yes
17/173 ... yes
45/174 ... yes
45/175 ... yes
45/176 ... yes
45/177 ... yes
2/179 ... yes
54/180 ... yes
17/181 ... yes
17/182 ... yes
24/183 ... yes
54/185 ... yes
48/186 ... yes
48/187 ... yes
3/188 ... yes
36/189 ... yes
28/190 ... yes
Redis version >= 2.8.0? ... yes
Ruby version >= 2.3.5 ? ... yes (2.3.6)
Git version >= 2.9.5 ? ... yes (2.14.3)
Git user has default SSH configuration? ... yes
Active users: ... 25
Checking GitLab ... Finished

Possible fixes

(If you can, link to the line of code that might be responsible for the problem)