Self-hosted instance does not load files on some repos, MRs do not load anymore either

Summary

Files do not load on specific (older) repositories, merge requests aren't listed anymore on my self-hosted GitLab instance either on specific older repositories.

Steps to reproduce

This is hard to say when it happened, how and why (and it's only for some , but for what I know:

1. Click on a specific repository on the repo view.
2. Files do not load
3. View the merge requests on a repo affected by step two.
4. This will also not load.

What is the current bug behavior?

Files do not load on specific repositories, neither do merge requests. When going into the repository settings, Unable to load the merge request options settings. Try reloading the page. will also appear.

What is the expected correct behavior?

It should work properly.

Relevant logs and/or screenshots

Nothing is shown in the browser console, also no odd HTTP replies are received.

Output of checks

Results of GitLab environment info

Expand for output related to GitLab environment info

System information
System:         Ubuntu 20.04
Proxy:          no
Current User:   git
Using RVM:      no
Ruby Version:   2.7.5p203
Gem Version:    3.1.4
Bundler Version:2.1.4
Rake Version:   13.0.6
Redis Version:  6.0.16
Git Version:    2.33.1.
Sidekiq Version:6.3.1
Go Version:     unknown

GitLab information
Version:        14.7.2-ee
Revision:       39a169b2f25
Directory:      /opt/gitlab/embedded/service/gitlab-rails
DB Adapter:     PostgreSQL
DB Version:     12.7
URL:            https://gitlab.masterwayz.nl
HTTP Clone URL: https://gitlab.masterwayz.nl/some-group/some-project.git
SSH Clone URL:  git@gitlab.masterwayz.nl:some-group/some-project.git
Elasticsearch:  no
Geo:            no
Using LDAP:     no
Using Omniauth: yes
Omniauth Providers:

GitLab Shell
Version:        13.22.2
Repository storage paths:
- default:      /var/opt/gitlab/git-data/repositories
GitLab Shell path:              /opt/gitlab/embedded/service/gitlab-shell
Git:            /opt/gitlab/embedded/bin/git

Results of GitLab application Check

Expand for output related to the GitLab application check

Checking GitLab subtasks ...
Checking GitLab Shell ...
GitLab Shell: ... GitLab Shell version >= 13.22.2 ? ... OK (13.22.2)
Running /opt/gitlab/embedded/service/gitlab-shell/bin/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 gitlab-incoming@masterwayz.nl
no
Try fixing it:
An error occurred: Net::IMAP::Error: connection closed
Check that the information in config/gitlab.yml is correct
For more information see:
doc/administration/reply_by_email.md
Please fix the error above and rerun the checks.
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 ...
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
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: ...
2/3 ... yes
2/7 ... yes
2/9 ... yes
2/10 ... yes
2/11 ... yes
2/12 ... yes
2/13 ... yes
2/16 ... yes
26/17 ... yes
2/18 ... yes
2/19 ... yes
2/20 ... yes
2/22 ... yes
2/23 ... yes
2/24 ... yes
26/25 ... yes
2/26 ... yes
2/27 ... yes
2/30 ... yes
2/31 ... yes
2/33 ... yes
2/34 ... yes
2/35 ... yes
2/36 ... yes
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2/38 ... yes
2/40 ... yes
2/41 ... yes
2/42 ... yes
2/43 ... yes
2/44 ... yes
2/45 ... yes
2/46 ... yes
2/47 ... yes
2/48 ... yes
2/49 ... yes
2/50 ... yes
2/51 ... yes
2/52 ... yes
2/53 ... yes
2/56 ... yes
2/57 ... yes
2/58 ... yes
2/59 ... yes
2/60 ... yes
2/61 ... yes
2/62 ... yes
2/64 ... yes
26/65 ... yes
26/66 ... yes
2/67 ... yes
26/69 ... yes
2/71 ... yes
2/72 ... yes
2/73 ... yes
2/74 ... yes
2/78 ... yes
2/79 ... yes
2/80 ... yes
2/81 ... yes
26/83 ... yes
26/84 ... yes
2/85 ... yes
2/86 ... yes
2/88 ... yes
2/89 ... yes
2/90 ... yes
2/91 ... yes
2/92 ... yes
2/93 ... yes
2/95 ... yes
2/96 ... yes
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2/100 ... yes
2/102 ... yes
2/103 ... yes
22/104 ... yes
2/106 ... yes
2/107 ... yes
2/108 ... yes
2/112 ... yes
2/113 ... yes
2/114 ... yes
2/115 ... yes
2/116 ... yes
26/117 ... yes
2/118 ... yes
2/119 ... yes
2/120 ... yes
2/121 ... yes
2/122 ... yes
2/123 ... yes
2/126 ... yes
2/127 ... yes
2/128 ... yes
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2/131 ... yes
2/132 ... yes
2/133 ... yes
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2/135 ... yes
2/136 ... yes
2/137 ... yes
2/138 ... yes
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2/140 ... yes
2/141 ... yes
2/143 ... yes
2/145 ... yes
2/146 ... yes
2/148 ... yes
2/149 ... yes
2/150 ... yes
2/151 ... yes
2/152 ... yes
2/153 ... yes
27/154 ... yes
2/155 ... yes
2/156 ... yes
27/157 ... yes
2/158 ... yes
2/159 ... yes
27/160 ... yes
32/161 ... yes
2/162 ... yes
2/164 ... yes
2/165 ... yes
2/166 ... yes
2/167 ... yes
2/168 ... yes
2/169 ... yes
2/171 ... yes
2/172 ... yes
2/174 ... yes
2/175 ... yes
27/176 ... yes
2/177 ... yes
2/178 ... yes
2/179 ... yes
2/180 ... yes
2/181 ... yes
2/182 ... yes
2/184 ... yes
2/185 ... yes
2/186 ... yes
2/187 ... yes
2/188 ... yes
2/189 ... yes
2/190 ... yes
2/191 ... yes
2/192 ... yes
2/193 ... yes
2/194 ... yes
2/195 ... yes
2/196 ... yes
2/197 ... yes
2/198 ... yes
2/199 ... yes
2/200 ... yes
2/201 ... yes
2/202 ... yes
2/203 ... yes
2/204 ... yes
2/205 ... yes
Redis version >= 5.0.0? ... yes
Ruby version >= 2.7.2 ? ... yes (2.7.5)
Git version >= 2.33.0 ? ... yes (2.33.1)
Git user has default SSH configuration? ... yes
Active users: ... 4
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 (6.4 - 6.x deprecated to be removed in 13.8)? ... skipped (elasticsearch is disabled)
Checking GitLab App ... Finished
Checking GitLab subtasks ... Finished

Possible fixes