Mail APP: Blank page

Nextcloud version: 25.0.2-1 (installation from repository)
Operating system and version: Manjaro Linux 22 (Arch Linux based)
Apache or nginx version: apache 2.4.54-3
PHP version : 8.1.13-4

The issue you are facing:

Is this the first time you’ve seen this error?: Yes

Steps to replicate it:

  1. Open Mail app page
  2. Observe “blank” page
  3. Sorrow

This is first time I’m trying Mail app, so I don’t know if it worked before.

By “blank” page I mean, that top menu header is OK, page background is loaded, but app contents are missing.

I did a small investigation, and this is what I have discovered: there are javascript errors when loading mail app page.

Resource with "https://pik-pik.ee/nextcloud/wapps/mail/js/mail.546.1526a0a69ddee1dd333c.js" was blocked due to mismatch of MIME type ("text/html") (X-Content-Type -Options: sniff).
Resource with "https://pik-pik.ee/nextcloud/wapps/mail/js/mail.276.e6df2ff30581b285ab09.js" was blocked due to mismatch of MIME type ("text/html") (X-Content-Type -Options: sniff).

This is due, that these files are missing, and what it actually loads is a page that redirects to login page, that’s why it is text/html. I can see that also in apache access logs:

84.52.56.150 - - [02/Jan/2023:13:57:54 +0200] "GET /nextcloud/wapps/mail/js/mail.546.1526a0a69ddee1dd333c.js HTTP/1.1" 404 - "-" "Mozilla/5.0 (X11; Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108.0"
84.52.56.150 - - [02/Jan/2023:13:57:54 +0200] "GET /nextcloud/wapps/mail/js/mail.276.e6df2ff30581b285ab09.js HTTP/1.1" 404 - "-" "Mozilla/5.0 (X11; Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108.0"

I checked the folder that contains these script files:

[pik-pik js]# ls -l
итого 35744
-rw-r--r-- 1 nextcloud nextcloud     206 24. dets  16:21 2e4d3cbdb67ee5310028.svg
-rw-r--r-- 1 nextcloud nextcloud     168 24. dets  16:21 2eaf8b262f4672598c6a.svg
-rw-r--r-- 1 nextcloud nextcloud     230 24. dets  16:21 autoredirect.js
-rw-r--r-- 1 nextcloud nextcloud     854 24. dets  16:21 autoredirect.js.LICENSE.txt
-rw-r--r-- 1 nextcloud nextcloud    1344 24. dets  16:21 autoredirect.js.map
-rw-r--r-- 1 nextcloud nextcloud 1107428 24. dets  16:21 dashboard.js
-rw-r--r-- 1 nextcloud nextcloud   14879 24. dets  16:21 dashboard.js.LICENSE.txt
-rw-r--r-- 1 nextcloud nextcloud 3533380 24. dets  16:21 dashboard.js.map
-rw-r--r-- 1 nextcloud nextcloud  109924 24. dets  16:21 googleoauthpopup.js
-rw-r--r-- 1 nextcloud nextcloud     864 24. dets  16:21 googleoauthpopup.js.LICENSE.txt
-rw-r--r-- 1 nextcloud nextcloud  632381 24. dets  16:21 googleoauthpopup.js.map
-rw-r--r-- 1 nextcloud nextcloud   19973 24. dets  16:21 htmlresponse.js
-rw-r--r-- 1 nextcloud nextcloud     840 24. dets  16:21 htmlresponse.js.LICENSE.txt
-rw-r--r-- 1 nextcloud nextcloud   77333 24. dets  16:21 htmlresponse.js.map
-rw-r--r-- 1 nextcloud nextcloud  279788 24. dets  16:21 mail.177.b13c0349e9565e741e8a.js
-rw-r--r-- 1 nextcloud nextcloud  408837 24. dets  16:21 mail.177.b13c0349e9565e741e8a.js.map
-rw-r--r-- 1 nextcloud nextcloud    4294 24. dets  16:21 mail.276.fd241c4b3959c51d0f15.js
-rw-r--r-- 1 nextcloud nextcloud   11003 24. dets  16:21 mail.276.fd241c4b3959c51d0f15.js.map
-rw-r--r-- 1 nextcloud nextcloud  595636 24. dets  16:21 mail.462.9d85d64cc762fbe8cbec.js
-rw-r--r-- 1 nextcloud nextcloud    4436 24. dets  16:21 mail.462.9d85d64cc762fbe8cbec.js.LICENSE.txt
-rw-r--r-- 1 nextcloud nextcloud 1018267 24. dets  16:21 mail.462.9d85d64cc762fbe8cbec.js.map
-rw-r--r-- 1 nextcloud nextcloud 4605605 24. dets  16:21 mail.489.8245318d2ed2e021bfce.js
-rw-r--r-- 1 nextcloud nextcloud    3946 24. dets  16:21 mail.489.8245318d2ed2e021bfce.js.LICENSE.txt
-rw-r--r-- 1 nextcloud nextcloud 9640429 24. dets  16:21 mail.489.8245318d2ed2e021bfce.js.map
-rw-r--r-- 1 nextcloud nextcloud  366708 24. dets  16:21 mail.546.fe28e799fec76c813af2.js
-rw-r--r-- 1 nextcloud nextcloud    5058 24. dets  16:21 mail.546.fe28e799fec76c813af2.js.LICENSE.txt
-rw-r--r-- 1 nextcloud nextcloud  523973 24. dets  16:21 mail.546.fe28e799fec76c813af2.js.map
-rw-r--r-- 1 nextcloud nextcloud 1507455 24. dets  16:21 mail.754.79474d1440a7f51955ec.js
-rw-r--r-- 1 nextcloud nextcloud    1034 24. dets  16:21 mail.754.79474d1440a7f51955ec.js.LICENSE.txt
-rw-r--r-- 1 nextcloud nextcloud 2942657 24. dets  16:21 mail.754.79474d1440a7f51955ec.js.map
-rw-r--r-- 1 nextcloud nextcloud 1574424 24. dets  16:21 mail.js
-rw-r--r-- 1 nextcloud nextcloud   12201 24. dets  16:21 mail.js.LICENSE.txt
-rw-r--r-- 1 nextcloud nextcloud 4930746 24. dets  16:21 mail.js.map
-rw-r--r-- 1 nextcloud nextcloud  638573 24. dets  16:21 settings.js
-rw-r--r-- 1 nextcloud nextcloud    1941 24. dets  16:21 settings.js.LICENSE.txt
-rw-r--r-- 1 nextcloud nextcloud 1941726 24. dets  16:21 settings.js.map
drwxr-xr-x 2 nextcloud nextcloud    4096 24. dets  16:21 translations
[pik-pik js]# pwd
/var/lib/nextcloud/apps/mail/js
[pik-pik js]#

The folder does contain mail.546.*.js and mail.276.*.js files, but they have different hash values. I don’t know what these mean.

Why Nextcloud requests javascript files with wrong hash values?

I could kinda copy or make a symbolic link to match requested file, but this would just heal symptoms, not the root cause.

I have a guess, that at some point upgrade process messed up. I started using since around version nextcloud-18.0.4 and kept updating to this date.

Please support =^.^= uwu




The output of your Nextcloud log in Admin > Logging:

log viewer is broken currently, (https://github.com/nextcloud/logreader/issues/699)
so i paste piece of nextcloud.log file,
when mail app page requested:

{"reqId":"Y7LE04t_ClLsrzUlaAIaJgAAAAo","level":0,"time":"2023-01-02T11:49:39+00:00","remoteAddr":"84.52.56.150","user":"ValkaTR","app":"mus
ic","method":"PROPFIND","url":"/nextcloud/remote.php/dav/files/ValkaTR/","message":"/appinfo/app.php is deprecated, use \\OCP\\AppFramework
\\Bootstrap\\IBootstrap on the application class instead.","userAgent":"Mozilla/5.0 (Linux) mirall/3.6.4git (Nextcloud, manjaro-6.1.0-1-MAN
JARO ClientArchitecture: x86_64 OsArchitecture: x86_64)","version":"25.0.2.3","data":{"app":"music"}}                                      
{"reqId":"Y7LE04AyQwP7IPbOBJtxBQAAAAg","level":0,"time":"2023-01-02T11:49:39+00:00","remoteAddr":"84.52.56.150","user":"ValkaTR","app":"mus
ic","method":"GET","url":"/nextcloud/apps/mail/","message":"/appinfo/app.php is deprecated, use \\OCP\\AppFramework\\Bootstrap\\IBootstrap 
on the application class instead.","userAgent":"Mozilla/5.0 (X11; Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108.0","version":"25.0.2.3
","data":{"app":"music"}}                                                                                                                  
{"reqId":"Y7LE1IAyQwP7IPbOBJtxBgAAAAg","level":0,"time":"2023-01-02T11:49:40+00:00","remoteAddr":"84.52.56.150","user":"ValkaTR","app":"mus
ic","method":"GET","url":"/nextcloud/apps/theming/image/logoheader?v=6","message":"/appinfo/app.php is deprecated, use \\OCP\\AppFramework\
\Bootstrap\\IBootstrap on the application class instead.","userAgent":"Mozilla/5.0 (X11; Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108
.0","version":"25.0.2.3","data":{"app":"music"}}                                                                                           
{"reqId":"Y7LE1IAyQwP7IPbOBJtxBwAAAAg","level":0,"time":"2023-01-02T11:49:40+00:00","remoteAddr":"84.52.56.150","user":"ValkaTR","app":"mus
ic","method":"GET","url":"/nextcloud/ocs/v2.php/search/providers?from=%2Fnextcloud%2Fapps%2Fmail%2F","message":"/appinfo/app.php is depreca
ted, use \\OCP\\AppFramework\\Bootstrap\\IBootstrap on the application class instead.","userAgent":"Mozilla/5.0 (X11; Linux x86_64; rv:108.
0) Gecko/20100101 Firefox/108.0","version":"25.0.2.3","data":{"app":"music"}}                                                              
{"reqId":"Y7LE1IAyQwP7IPbOBJtxCAAAAAg","level":0,"time":"2023-01-02T11:49:40+00:00","remoteAddr":"84.52.56.150","user":"ValkaTR","app":"mus
ic","method":"GET","url":"/nextcloud/ocs/v2.php/apps/notifications/api/v2/notifications","message":"/appinfo/app.php is deprecated, use \\O
CP\\AppFramework\\Bootstrap\\IBootstrap on the application class instead.","userAgent":"Mozilla/5.0 (X11; Linux x86_64; rv:108.0) Gecko/201
00101 Firefox/108.0","version":"25.0.2.3","data":{"app":"music"}}                                                                          
{"reqId":"Y7LE1JdURzqUUsJBdWT10AAAAAI","level":0,"time":"2023-01-02T11:49:40+00:00","remoteAddr":"84.52.56.150","user":"ValkaTR","app":"mus
ic","method":"PUT","url":"/nextcloud/ocs/v2.php/apps/user_status/api/v1/heartbeat?format=json","message":"/appinfo/app.php is deprecated, u
se \\OCP\\AppFramework\\Bootstrap\\IBootstrap on the application class instead.","userAgent":"Mozilla/5.0 (X11; Linux x86_64; rv:108.0) Gec
ko/20100101 Firefox/108.0","version":"25.0.2.3","data":{"app":"music"}}                                                                    
{"reqId":"Y7LE1NsFNLmhd-K80pC-CAAAAAc","level":0,"time":"2023-01-02T11:49:40+00:00","remoteAddr":"84.52.56.150","user":"ValkaTR","app":"mus
ic","method":"GET","url":"/nextcloud/wapps/mail/js/mail.546.1526a0a69ddee1dd333c.js","message":"/appinfo/app.php is deprecated, use \\OCP\\
AppFramework\\Bootstrap\\IBootstrap on the application class instead.","userAgent":"Mozilla/5.0 (X11; Linux x86_64; rv:108.0) Gecko/2010010
1 Firefox/108.0","version":"25.0.2.3","data":{"app":"music"}}                                                                              
{"reqId":"Y7LE1B3MWAam7F7-Lv8PLAAAAAA","level":0,"time":"2023-01-02T11:49:41+00:00","remoteAddr":"84.52.56.150","user":"ValkaTR","app":"mus
ic","method":"GET","url":"/nextcloud/wapps/mail/js/mail.276.e6df2ff30581b285ab09.js","message":"/appinfo/app.php is deprecated, use \\OCP\\
AppFramework\\Bootstrap\\IBootstrap on the application class instead.","userAgent":"Mozilla/5.0 (X11; Linux x86_64; rv:108.0) Gecko/2010010
1 Firefox/108.0","version":"25.0.2.3","data":{"app":"music"}}                                                                              
{"reqId":"Y7LE1JdURzqUUsJBdWT10QAAAAI","level":0,"time":"2023-01-02T11:49:41+00:00","remoteAddr":"84.52.56.150","user":"ValkaTR","app":"mus
ic","method":"PROPFIND","url":"/nextcloud/remote.php/dav/","message":"/appinfo/app.php is deprecated, use \\OCP\\AppFramework\\Bootstrap\\I
Bootstrap on the application class instead.","userAgent":"Mozilla/5.0 (X11; Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108.0","version"
:"25.0.2.3","data":{"app":"music"}}
{"reqId":"Y7LE1YAyQwP7IPbOBJtxCQAAAAg","level":0,"time":"2023-01-02T11:49:41+00:00","remoteAddr":"84.52.56.150","user":"ValkaTR","app":"mus
ic","method":"PROPFIND","url":"/nextcloud/remote.php/dav/principals/users/ValkaTR/","message":"/appinfo/app.php is deprecated, use \\OCP\\A
ppFramework\\Bootstrap\\IBootstrap on the application class instead.","userAgent":"Mozilla/5.0 (X11; Linux x86_64; rv:108.0) Gecko/20100101
 Firefox/108.0","version":"25.0.2.3","data":{"app":"music"}}                                                                               
{"reqId":"Y7LE1YAyQwP7IPbOBJtxCgAAAAg","level":0,"time":"2023-01-02T11:49:42+00:00","remoteAddr":"84.52.56.150","user":"ValkaTR","app":"mus
ic","method":"PROPFIND","url":"/nextcloud/remote.php/dav/calendars/ValkaTR/","message":"/appinfo/app.php is deprecated, use \\OCP\\AppFrame
work\\Bootstrap\\IBootstrap on the application class instead.","userAgent":"Mozilla/5.0 (X11; Linux x86_64; rv:108.0) Gecko/20100101 Firefo
x/108.0","version":"25.0.2.3","data":{"app":"music"}}

The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):

<?php
$CONFIG = array (
  'instanceid' => '############',
  'passwordsalt' => '##############################',
  'secret' => '################################################',
  'trusted_domains' => 
  array (
    0 => 'pik-pik.ee'
  ),
  'datadirectory' => '/var/nextcloud',
  'dbtype' => 'mysql',
  'version' => '25.0.2.3',
  'overwrite.cli.url' => 'http://pik-pik.ee/nextcloud',
  'htaccess.RewriteBase' => '/nextcloud',
  'dbname' => '#############',
  'dbhost' => 'localhost',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'mysql.utf8mb4' => true,
  'dbuser' => '#############',
  'dbpassword' => '#############',
  'installed' => true,
  'theme' => '',
  'loglevel' => 0,
  'logfile' => '/var/log/nextcloud/nextcloud.log',
  'maintenance' => false,
  'mail_from_address' => 'admin',
  'mail_smtpmode' => 'smtp',
  'mail_sendmailmode' => 'smtp',
  'mail_domain' => 'pik-pik.ee',
  'enable_previews' => true,
  'enabledPreviewProviders' => 
  array (
    0 => 'OC\\Preview\\TXT',
    1 => 'OC\\Preview\\MarkDown',
    2 => 'OC\\Preview\\OpenDocument',
    3 => 'OC\\Preview\\PDF',
    4 => 'OC\\Preview\\MSOffice2003',
    5 => 'OC\\Preview\\MSOfficeDoc',
    6 => 'OC\\Preview\\Image',
    7 => 'OC\\Preview\\Photoshop',
    8 => 'OC\\Preview\\TIFF',
    9 => 'OC\\Preview\\SVG',
    10 => 'OC\\Preview\\Font',
    11 => 'OC\\Preview\\MP3',
    12 => 'OC\\Preview\\Movie',
    13 => 'OC\\Preview\\MKV',
    14 => 'OC\\Preview\\MP4',
    15 => 'OC\\Preview\\AVI',
  ),
  'apps_paths' => 
  array (
    0 => 
    array (
      'path' => '/usr/share/webapps/nextcloud/apps',
      'url' => '/apps',
      'writable' => false,
    ),
    1 => 
    array (
      'path' => '/var/lib/nextcloud/apps',
      'url' => '/wapps',
      'writable' => true,
    ),
  ),
  'app_install_overwrite' => 
  array (
    0 => 'music',
  ),
  'mail_smtphost' => 'pik-pik.ee',
  'mail_smtpport' => '587',
  'mail_smtpsecure' => 'tls',
  'mail_smtpauth' => 1,
  'mail_smtpname' => '###############',
  'mail_smtppassword' => '##################',
);

The output of your Apache/nginx/system log in /var/log/____:

84.52.56.150 - - [02/Jan/2023:13:57:52 +0200] "GET /nextcloud/apps/mail/ HTTP/1.1" 200 13701 "-" "Mozilla/5.0 (X11; Linux x86_64; rv:108.0)
 Gecko/20100101 Firefox/108.0"                                                                                                             
84.52.56.150 - - [02/Jan/2023:13:57:53 +0200] "GET /nextcloud/apps/theming/image/logoheader?v=6 HTTP/1.1" 404 31006 "-" "Mozilla/5.0 (X11; 
Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108.0"                                                                                      
84.52.56.150 - - [02/Jan/2023:13:57:53 +0200] "GET /nextcloud/dist/core-common.js.map?v=c696e133421bbeb9dc14 HTTP/1.1" 304 - "-" "Mozilla/5
.0 (X11; Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108.0"                                                                             
84.52.56.150 - - [02/Jan/2023:13:57:53 +0200] "GET /nextcloud/ocs/v2.php/search/providers?from=%2Fnextcloud%2Fapps%2Fmail%2F HTTP/1.1" 200 
409 "-" "Mozilla/5.0 (X11; Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108.0"                                                           
84.52.56.150 - - [02/Jan/2023:13:57:53 +0200] "PUT /nextcloud/ocs/v2.php/apps/user_status/api/v1/heartbeat?format=json HTTP/1.1" 200 129 "-
" "Mozilla/5.0 (X11; Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108.0"                                                                 
84.52.56.150 - - [02/Jan/2023:13:57:53 +0200] "GET /nextcloud/ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 558 "-" "Moz
illa/5.0 (X11; Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108.0"                                                                       
84.52.56.150 - - [02/Jan/2023:13:57:53 +0200] "GET /nextcloud/apps/theming/image/logoheader?v=6 HTTP/1.1" 404 31006 "-" "Mozilla/5.0 (X11; 
Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108.0"                                                                                      
84.52.56.150 - - [02/Jan/2023:13:57:54 +0200] "GET /nextcloud/wapps/mail/js/mail.546.1526a0a69ddee1dd333c.js HTTP/1.1" 404 - "-" "Mozilla/5
.0 (X11; Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108.0"                                                                             
84.52.56.150 - - [02/Jan/2023:13:57:54 +0200] "GET /nextcloud/wapps/mail/js/mail.276.e6df2ff30581b285ab09.js HTTP/1.1" 404 - "-" "Mozilla/5
.0 (X11; Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108.0"                                                                             
84.52.56.150 - - [02/Jan/2023:13:57:54 +0200] "PROPFIND /nextcloud/remote.php/dav/ HTTP/1.1" 207 236 "-" "Mozilla/5.0 (X11; Linux x86_64; r
v:108.0) Gecko/20100101 Firefox/108.0"                                                                                                     
84.52.56.150 - - [02/Jan/2023:13:57:54 +0200] "PROPFIND /nextcloud/remote.php/dav/principals/users/ValkaTR/ HTTP/1.1" 207 710 "-" "Mozilla/
5.0 (X11; Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108.0"                                                                            
84.52.56.150 - - [02/Jan/2023:13:57:55 +0200] "GET /nextcloud/apps/viewer/js/viewer-main.js.map?v=1c9fb1762206f91e2b47 HTTP/1.1" 304 - "-" 
"Mozilla/5.0 (X11; Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108.0"                                                                   
84.52.56.150 - - [02/Jan/2023:13:57:55 +0200] "GET /nextcloud/wapps/richdocuments/js/richdocuments-viewer.js.map?v=75a18a4eb1c38903e22e HTT
P/1.1" 304 - "-" "Mozilla/5.0 (X11; Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108.0"                                                  
84.52.56.150 - - [02/Jan/2023:13:57:55 +0200] "GET /nextcloud/apps/text/js/text-viewer.js.map?v=4a5e8b07b5ca655190cf HTTP/1.1" 304 - "-" "M
ozilla/5.0 (X11; Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108.0"                                                                     
84.52.56.150 - - [02/Jan/2023:13:57:55 +0200] "GET /nextcloud/apps/notifications/js/notifications-main.js.map?v=64314571dd6f8477ff87 HTTP/1
.1" 304 - "-" "Mozilla/5.0 (X11; Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108.0"                                                     
84.52.56.150 - - [02/Jan/2023:13:57:55 +0200] "GET /nextcloud/dist/core-main.js.map?v=925f3f6cf2d1e7fc1152 HTTP/1.1" 304 - "-" "Mozilla/5.0
 (X11; Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108.0"                                                                               
84.52.56.150 - - [02/Jan/2023:13:57:55 +0200] "GET /nextcloud/apps/mail/js/mail.js.map HTTP/1.1" 304 - "-" "Mozilla/5.0 (X11; Linux x86_64;
 rv:108.0) Gecko/20100101 Firefox/108.0"                                                                                                   
84.52.56.150 - - [02/Jan/2023:13:57:54 +0200] "PROPFIND /nextcloud/remote.php/dav/calendars/ValkaTR/ HTTP/1.1" 207 1687 "-" "Mozilla/5.0 (X
11; Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108.0"

Investigation update:

I have two nearly identical folders for mail app:

/usr/share/webapps/nextcloud/apps/mail/
(https://localhost/nextcloud/apps/mail/)

/var/lib/nextcloud/apps/mail/
(https://localhost/nextcloud/wapps/mail/)

The difference is these javascript files, that mail app cannot load:

[pik-pik js]# LC_ALL="C" diff -q /usr/share/webapps/nextcloud/apps/mail/js/ /var/lib/nextcloud/apps/mail/js/
Only in /usr/share/webapps/nextcloud/apps/mail/js/: mail.276.e6df2ff30581b285ab09.js
Only in /usr/share/webapps/nextcloud/apps/mail/js/: mail.276.e6df2ff30581b285ab09.js.map
Only in /var/lib/nextcloud/apps/mail/js/: mail.276.fd241c4b3959c51d0f15.js
Only in /var/lib/nextcloud/apps/mail/js/: mail.276.fd241c4b3959c51d0f15.js.map
Only in /usr/share/webapps/nextcloud/apps/mail/js/: mail.546.1526a0a69ddee1dd333c.js
Only in /usr/share/webapps/nextcloud/apps/mail/js/: mail.546.1526a0a69ddee1dd333c.js.LICENSE.txt
Only in /usr/share/webapps/nextcloud/apps/mail/js/: mail.546.1526a0a69ddee1dd333c.js.map
Only in /var/lib/nextcloud/apps/mail/js/: mail.546.fe28e799fec76c813af2.js
Only in /var/lib/nextcloud/apps/mail/js/: mail.546.fe28e799fec76c813af2.js.LICENSE.txt
Only in /var/lib/nextcloud/apps/mail/js/: mail.546.fe28e799fec76c813af2.js.map
Files /usr/share/webapps/nextcloud/apps/mail/js/mail.js and /var/lib/nextcloud/apps/mail/js/mail.js differ
Files /usr/share/webapps/nextcloud/apps/mail/js/mail.js.map and /var/lib/nextcloud/apps/mail/js/mail.js.map differ
Common subdirectories: /usr/share/webapps/nextcloud/apps/mail/js/translations and /var/lib/nextcloud/apps/mail/js/translations
[pik-pik js]#

ok, so symbolic links did indeed fix the issue:

# ln -s -v /usr/share/webapps/nextcloud/apps/mail/js/mail.276.e6df2ff30581b285ab09.js /var/lib/nextcloud/apps/mail/js/mail.276.e6df2ff30581b285ab09.js
# ln -s -v /usr/share/webapps/nextcloud/apps/mail/js/mail.276.e6df2ff30581b285ab09.js.map /var/lib/nextcloud/apps/mail/js/mail.276.e6df2ff30581b285ab09.js.map
# ln -s -v /usr/share/webapps/nextcloud/apps/mail/js/mail.546.1526a0a69ddee1dd333c.js /var/lib/nextcloud/apps/mail/js/mail.546.1526a0a69ddee1dd333c.js
# ln -s -v /usr/share/webapps/nextcloud/apps/mail/js/mail.546.1526a0a69ddee1dd333c.js.map /var/lib/nextcloud/apps/mail/js/mail.546.1526a0a69ddee1dd333c.js.map
# ln -s -v /usr/share/webapps/nextcloud/apps/mail/js/mail.546.1526a0a69ddee1dd333c.js.LICENSE.txt /var/lib/nextcloud/apps/mail/js/mail.546.1526a0a69ddee1dd333c.js.LICENSE.txt

the mail app is now working,
but what the hell is going on here?

NextCloud updated to 26 version and issue emerged once again. Seems like updater removed all these symlinks and I had to make them again.

Why are your errors related to the music app. Does it work when you disable the music app?

Also check the vhost config of your apache server with the one in the documentation. Sometimes they improve stuff and if that misses some automated redirection or something, that could explain the issue.