I cant install plugins - 500 Internal Server Error

I cant install plugins in the wpmudev.
Following Error:
"Server error status: Internal Server Error [500]"

What can I do?

  • Kris
    • Support

    Hi Philipp Ludwig,

    Hope you are doing good today.

    There are many reasons why this error appear.
    On this article you can read more about it, and it is also a walkthrough how to fix this error or check what makes this issue:

    If you feel uncomfortable with some of those solutions I can do it for you. I will need your Support Access. To do that you can read this https://premium.wpmudev.org/docs/getting-started/getting-support/#chapter-5

    Also in this case I will need your FTP credentials to take a closer look on your htaccess / wp-config.php / php.ini files. Please send it through our secure contact form here https://premium.wpmudev.org/contact/#i-have-a-different-question and make sure that subject is "I have a different question" and:
    - Mark to my attention: ATTN: Krzysztof Tomczyk
    - FTP credentials (host / username / password)
    - Link back to this thread

    Please confirm here in thread that you have sent that message.

    Kind Regards,

  • Kris
    • Support

    Hi Philipp Ludwig,

    Thank you for all the data. I try to log in to your site but it's look like there is some issue with your database.

    I try to add to your wp-config.php file this line:
    define('WP_ALLOW_REPAIR', true);
    and repair the databaseand by hiting this address /wp-admin/maint/repair.php but I got "Error establishing a database connection" error.

    I check in your wp-config.php database access and the password is different from that one you send me on helpscout. I can't at this point change the password in your wp-config.php because this could break the site.
    Can you first make a:
    - full backup of your site (files and database)
    - check what is the correct password to your database and update it in your wp-config.php
    - try to log in to your dashboard

    Please confirm that you able to log in to your site after those steps.

    After that I can proceed to check what is the issue with installing our plugins on your site.

    Kind Regards,

  • Kris
    • Support

    Hi Philipp Ludwig,

    I was able to log in to your site and your FTP.

    I also check you server settings and it looks good:
    max_execution_time is set to 300
    memory_limit is set to 256M
    upload_max_filesize is set to 128M
    post_max_size is set to 130M

    I added this code to your wp-config.php file:

    define('WP_DEBUG', true);
    define('WP_DEBUG_LOG', true);
    define('WP_DEBUG_DISPLAY', false);

    to understand what is causing the error.

    From what I see in debug.log file during installation there is an error:
    PHP Fatal error: Uncaught Error: Class 'WP_Ajax_Upgrader_Skin'

    From what I searched in the support forum, this issue may be related to the outdated version of WordPress.
    Can you first make a:
    - full backup of your site and database,
    - upgrade WordPress to new version (current is 4.8.3)
    - try to install our plugins

    Kind Regards,

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