This is the output i am getting:

jailshell-4.1$ composer update --prefer-dist --no-dev -a --with-all-dependencies
Loading composer repositories with package information
Updating dependencies
Nothing to install or update
Generating optimized autoload files
Carbon 1 is deprecated, see how to migrate to Carbon 2.
https://carbon.nesbot.com/docs/#api-carbon-2
You can run './vendor/bin/upgrade-carbon' to get help in updating carbon and other frameworks and libraries that depend on it.
jailshell-4.1$

love_from_india fof/upload

You need to update upload:

composer require fof/upload
composer update --with-all-dependencies

    luceos It seems flarum core has been updated with beta 13. However its not showing on front end of forum. Below is the output of update.

    jailshell-4.1$ composer update --prefer-dist --no-dev -a --with-all-dependencies
    Loading composer repositories with package information
    Updating dependencies
    Package operations: 0 installs, 21 updates, 0 removals

    • Updating wikimedia/less.php (v2.0.0 => v3.0.0): Downloading (100%)
    • Updating flarum/core (v0.1.0-beta.12 => v0.1.0-beta.13): Downloading (100%)
    • Updating flarum/flags (v0.1.0-beta.12 => v0.1.0-beta.13): Downloading (100%)
    • Updating flarum/approval (v0.1.0-beta.12 => v0.1.0-beta.13): Downloading (100%)
    • Updating flarum/auth-facebook (v0.1.0-beta.12 => v0.1.0-beta.13): Downloading (100%)
    • Updating flarum/auth-github (v0.1.0-beta.12 => v0.1.0-beta.13): Downloading (100%)
    • Updating flarum/auth-twitter (v0.1.0-beta.12 => v0.1.0-beta.13): Downloading (100%)
    • Updating flarum/emoji (v0.1.0-beta.12 => v0.1.0-beta.13): Downloading (100%)
    • Updating flarum/lang-english (v0.1.0-beta.12 => v0.1.0-beta.13): Downloading (100%)
    • Updating flarum/likes (v0.1.0-beta.12 => v0.1.0-beta.13): Downloading (100%)
    • Updating flarum/lock (v0.1.0-beta.12 => v0.1.0-beta.13): Downloading (100%)
    • Updating flarum/markdown (v0.1.0-beta.12 => v0.1.0-beta.13): Downloading (100%)
    • Updating flarum/mentions (v0.1.0-beta.12 => v0.1.0-beta.13): Downloading (100%)
    • Updating flarum/pusher (v0.1.0-beta.12 => v0.1.0-beta.13): Downloading (100%)
    • Updating flarum/statistics (v0.1.0-beta.12 => v0.1.0-beta.13): Downloading (100%)
    • Updating flarum/sticky (v0.1.0-beta.12 => v0.1.0-beta.13): Downloading (100%)
    • Updating flarum/subscriptions (v0.1.0-beta.12 => v0.1.0-beta.13): Downloading (100%)
    • Updating flarum/suspend (v0.1.0-beta.12 => v0.1.0-beta.13): Downloading (100%)
    • Updating flarum/tags (v0.1.0-beta.12 => v0.1.0-beta.13): Downloading (100%)
    • Updating fof/best-answer (0.1.8 => 0.1.11): Downloading (100%)
    • Updating fof/drafts (0.1.10 => 0.1.12): Downloading (100%)
      Writing lock file
      Generating optimized autoload files
      Carbon 1 is deprecated, see how to migrate to Carbon 2.
      https://carbon.nesbot.com/docs/#api-carbon-2
      You can run './vendor/bin/upgrade-carbon' to get help in updating carbon and other frameworks and libraries that depend on it.
      jailshell-4.1$ php flarum migrate
      jailshell-4.1$ php flarum cache:clear

      luceos I am getting following output on running this command

      There is no no installed package depending on "flarum/core" in version not matching v0.1.0-beta.13

      Please help

      8 days later
      a month later

      Hello!

      I have the same problem.

      -bash-4.2$ php flarum info                                                                                                                   
      Flarum core 0.1.0-beta.12                                                                                                                    
      PHP version: 7.1.28                                                                                                                          
      Loaded extensions: Core, date, libxml, openssl, pcre, sqlite3, zlib, bz2, calendar, ctype, hash, fileinfo, filter, ftp, gettext, gmp, SPL, ic
      onv, pcntl, session, standard, readline, Reflection, Phar, shmop, SimpleXML, sockets, mbstring, tokenizer, xml, mysqlnd, PDO, curl, dom, gd, 
      json, exif, mcrypt, mysqli, pdo_mysql, soap, xmlrpc, ionCube Loader                                                                          
      +---------------------+----------------+--------+                                                                                            
      | Flarum Extensions   |                |        |                                                                                            
      +---------------------+----------------+--------+                                                                                            
      | ID                  | Version        | Commit |                                                                                            
      +---------------------+----------------+--------+                                                                                            
      | flarum-lang-english | v0.1.0-beta.12 |        |                                                                                            
      | flarum-flags        | v0.1.0-beta.12 |        |                                                                                            
      | flarum-likes        | v0.1.0-beta.12 |        |                                                                                            
      | flarum-lock         | v0.1.0-beta.12 |        |                                                                                            
      | flarum-markdown     | v0.1.0-beta.12 |        |                                                                                            
      | flarum-mentions     | v0.1.0-beta.12 |        |                                                                                            
      | flarum-sticky       | v0.1.0-beta.12 |        |                                                                                            
      | flarum-suspend      | v0.1.0-beta.12 |        |                                                                                            
      | flarum-bbcode       | v0.1.0-beta.12 |        |                                                                                            
      +---------------------+----------------+--------+                                                                                            
      Base URL: https://genir.ru                                                                                                                   
      Installation path: /var/www/genir.ru                                                                                          
      Debug mode: off                                         

      When executing the update command, it issues this:

      -bash-4.2$ composer update --prefer-dist --no-dev -a --with-all-dependencies                                                                 
      Loading composer repositories with package information
      Updating dependencies
      Nothing to install or update                                                                                                                 
      Package s9e/flarum-ext-autoimage is abandoned, you should avoid using it. Use fof/formatting instead.
      Package wiwatsrt/flarum-ext-best-answer is abandoned, you should avoid using it. No replacement was suggested.
      Generating optimized autoload files
      Carbon 1 is deprecated, see how to migrate to Carbon 2.                                                                                      
      https://carbon.nesbot.com/docs/#api-carbon-2                                                                                                 
          You can run './vendor/bin/upgrade-carbon' to get help in updating carbon and other frameworks and libraries that depend on it.

      I followed the advice and ran the command ./vendor/bin/upgrade-carbon

      Got the result:

      Using version ^1.10 for composer/composer                                                                                                    
      ./composer.json has been updated                                                                                                             
      Loading composer repositories with package information                                                                                       
      Updating dependencies (including require-dev)                                                                                                
      Package operations: 8 installs, 0 updates, 0 removals                                                                                        
        - Installing seld/phar-utils (1.1.1): Downloading (100%)                                                                                   
        - Installing seld/jsonlint (1.8.1): Downloading (100%)                                                                                     
        - Installing justinrainbow/json-schema (5.2.10): Downloading (100%)                                                                        
        - Installing composer/xdebug-handler (1.4.3): Downloading (100%)                                                                           
        - Installing composer/spdx-licenses (1.5.4): Downloading (100%)                                                                            
        - Installing composer/semver (1.5.1): Downloading (100%)                                                                                   
        - Installing composer/ca-bundle (1.2.7): Downloading (100%)                                                                                
        - Installing composer/composer (1.10.10): Downloading (100%)                                                                               
      composer/composer suggests installing ext-zip (Enabling the zip extension allows you to unzip archives)                                      
      Package s9e/flarum-ext-autoimage is abandoned, you should avoid using it. Use fof/formatting instead.                                        
      Package wiwatsrt/flarum-ext-best-answer is abandoned, you should avoid using it. No replacement was suggested.                               
      Writing lock file                                                                                                                            
      Generating autoload files                                                                                                                    
      5 packages you are using are looking for funding.                                                                                            
      Use the `composer fund` command to find out more!                                                                                            
      Do you want us to try the following upgrade:                                                                                                 
        - nesbot/carbon: ^2.0.0                                                                                                                    
      [Y/N] y                                                                                                                                      
      Loading composer repositories with package information                                                                                       
      Updating dependencies (including require-dev)                                                                                                
      Nothing to install or update                                                                                                                 
      Package s9e/flarum-ext-autoimage is abandoned, you should avoid using it. Use fof/formatting instead.                                        
      Package wiwatsrt/flarum-ext-best-answer is abandoned, you should avoid using it. No replacement was suggested.                               
      Generating autoload files                                                                                                                    
      5 packages you are using are looking for funding.                                                                                            
      Use the `composer fund` command to find out more!                                                                                            
      Loading composer repositories with package information                                                                                       
      Updating dependencies (including require-dev)                                                                                                
      Package operations: 0 installs, 0 updates, 8 removals                                                                                        
        - Removing seld/phar-utils (1.1.1)                                                                                                         
        - Removing seld/jsonlint (1.8.1)                                                                                                           
        - Removing justinrainbow/json-schema (5.2.10)                                                                                              
        - Removing composer/xdebug-handler (1.4.3)                                                                                                 
        - Removing composer/spdx-licenses (1.5.4)                                                                                                  
        - Removing composer/semver (1.5.1)                                                                                                         
        - Removing composer/composer (1.10.10)                                                                                                     
        - Removing composer/ca-bundle (1.2.7)                                                                                                      
      Package s9e/flarum-ext-autoimage is abandoned, you should avoid using it. Use fof/formatting instead.                                        
      Package wiwatsrt/flarum-ext-best-answer is abandoned, you should avoid using it. No replacement was suggested.                               
      Writing lock file                                                                                                                            
      Generating autoload files
      -bash-4.2$ composer why-not flarum/core v0.1.0-beta.13                                                                                       
      flarum/core    v0.1.0-beta.13  requires          php (>=7.2 but 7.1.28 is installed)                                                         
      flarum/core    v0.1.0-beta.13  requires          wikimedia/less.php (^3.0)                                                                   
      flarum/flarum  -               does not require  wikimedia/less.php (but v2.0.0 is installed)

      What am I doing wrong?

        Aleram The most major issue is that your using PHP 7.1 as of Beta.13 we require PHP 7.2 as the minimum standard (although we would actually recommend php 7.3 or 7.4) further you should remove the extensions listed as abandoned using:

        composer remove s9e/flarum-ext-autoimage
        composer remove wiwatsrt/flarum-ext-best-answer

          As Matt correctly points out, the why-not gives the reason with this line, just to be clear:

          Aleram flarum/core v0.1.0-beta.13 requires php (>=7.2 but 7.1.28 is installed)

            luceos tankerkiller125
            In general, the PHP version is installed 7.3.4

            -bash-4.2$ /opt/php73/bin/php -v
            PHP 7.3.4 (cli) (built: Apr 9 2019 12:37:40) ( NTS )
            Copyright (c) 1997-2018 The PHP Group
            Zend Engine v3.3.4, Copyright (c) 1998-2018 Zend Technologies

            I will sort this out. Thanks for the direction

            UPD
            After the forced change of the PHP, the update was successful.
            Thanks again for your help!