Behaviour when browsing photos in web interface

Nextcloud version (eg, 12.0.2): 18.0.1
Operating system and version (eg, Ubuntu 17.04): Debian 10
Apache or nginx version (eg, Apache 2.4.25): Apache 2.4.38
PHP version (eg, 7.1): 7.4

The issue you are facing: Different loading behaviour when clicking individually on a photo vs scrolling the same photos with cursor keys.

Is this the first time you’ve seen this error? (Y/N): N

Steps to replicate it:

  1. From my Nextcloud website, I open a folder full of photos.
  2. I click on a photo, it takes 2-3 seconds to open a frame and then shows the picture. I close the frame.
  3. I click on a different photo, same behaviour, 2-3 seconds to load the frame and show the photo.

But:

  1. From my Nextcloud website, I open a folder full of photos.
  2. I click on a photo, and once it’s loaded, I press left or right to browse the photos. They load instantly on screen, instead of taking these 2-3 seconds from the previous scenario.

To me it doesn’t make sense, why does it take so long to open a single photo, but then if I browse photos with arrow keys, they load instantly, all of them?

The output of your Nextcloud log in Admin > Logging:

Warning	core	Login failed: '' (Remote IP: 'xxx')		2020-03-03T14:08:26+0100
Error	PHP	Trying to access array offset on value of type null at /var/www/html/nextcloud/3rdparty/leafo/scssphp/src/Compiler.php#5230		2020-03-02T19:55:09+0100

(but that error is from yesterday and it hasn’t shown again)

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

<?php
$CONFIG = array (
  'instanceid' => '7',
  'passwordsalt' => ',
  'secret' => '
  'trusted_domains' => 
  array (
    0 => ',
  ),
  'datadirectory' => 
  'dbtype' => 'mysql',
  'version' => '18.0.1.3',
  'overwrite.cli.url' => 
  'dbname' => 'nextcloud',
  'dbhost' => 'localhost',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'mysql.utf8mb4' => true,
  'dbuser' => 'd',
  'dbpassword' =>
  'memcache.local' => '\\OC\\Memcache\\APCu',
  'installed' => true,
  'mail_smtpmode' => 'smtp',
  'mail_smtpauthtype' => 'LOGIN',
  'mail_sendmailmode' => 'smtp',
  'mail_from_address' => '',
  'mail_domain' =>
  'mail_smtpsecure' => 'tls',
  'mail_smtphost' => 
  'mail_smtpport' => '587',
  'mail_smtpauth' => 1,
  'mail_smtpname' => 
  'mail_smtppassword' => 
  'maintenance' => false,
  'has_rebuilt_cache' => true,
  'twofactor_enforced' => 'true',
  'twofactor_enforced_groups' => 
  array (
    0 => 'admin',
  ),
  'twofactor_enforced_excluded_groups' => 
  array (
  ),
);

The output of your Apache/nginx/system log in /var/log/apache2:

192.168.1.1 - - [03/Mar/2020:16:28:33 +0100] "PROPFIND /remote.php/dav/files/j/ HTTP/2.0" 207 841 "-" "Mozilla/5.0 (Windows) mirall/2.6.2stable-Win64 (build 20191224) (Nextcloud)"

(really nothing else of relevance)