Title: installation problem
Last modified: June 26, 2018

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# installation problem

 *  Resolved [songsta](https://wordpress.org/support/users/songsta/)
 * (@songsta)
 * [7 years, 11 months ago](https://wordpress.org/support/topic/installation-problem-141/)
 * Hi Etienne
 * I installed this plugin and got the following errors.
 * Constant PN_MSV_MAX_CONTENT_LENGTH – assumed ‘PN_MSV_MAX_CONTENT_LENGTH’ (this
   will throw an Error in a future version of PHP) in /var/www/html/wp-content/plugins/
   music-sheet-viewer/music-sheet-viewer.php on line 28
 * Warning: Use of undefined constant PN_MSV_MAX_CONTENT_LENGTH – assumed ‘PN_MSV_MAX_CONTENT_LENGTH’(
   this will throw an Error in a future version of PHP) in /var/www/html/wp-content/
   plugins/music-sheet-viewer/music-sheet-viewer.php on line 28
 * Warning: Use of undefined constant PN_MSV_DEBUGJS – assumed ‘PN_MSV_DEBUGJS’ (
   this will throw an Error in a future version of PHP) in /var/www/html/wp-content/
   plugins/music-sheet-viewer/music-sheet-viewer.php on line 29
 * Warning: Use of undefined constant PN_MSV_DEBUGJS – assumed ‘PN_MSV_DEBUGJS’ (
   this will throw an Error in a future version of PHP) in /var/www/html/wp-content/
   plugins/music-sheet-viewer/music-sheet-viewer.php on line 29
 * Warning: session_start(): Cannot start session when headers already sent in /
   var/www/html/wp-content/plugins/medium/lib/medium-admin.php on line 27
 * Warning: Cannot modify header information – headers already sent by (output started
   at /var/www/html/wp-content/plugins/music-sheet-viewer/music-sheet-viewer.php:
   28) in /var/www/html/wp-admin/includes/misc.php on line 1116
 * Warning: Cannot modify header information – headers already sent by (output started
   at /var/www/html/wp-content/plugins/music-sheet-viewer/music-sheet-viewer.php:
   28) in /var/www/html/wp-includes/option.php on line 919
 * Warning: Cannot modify header information – headers already sent by (output started
   at /var/www/html/wp-content/plugins/music-sheet-viewer/music-sheet-viewer.php:
   28) in /var/www/html/wp-includes/option.php on line 920

Viewing 4 replies - 1 through 4 (of 4 total)

 *  Plugin Author [efreja](https://wordpress.org/support/users/efreja/)
 * (@efreja)
 * [7 years, 11 months ago](https://wordpress.org/support/topic/installation-problem-141/#post-10438250)
 * Hi songsta,
    First of all this is only warnings so it’s possible that the plugin
   works however.. But this isn’t satisfactory. Have you checked the installation
   requirements : Requires WordPress Version:4.6.11 Requires PHP Version:7.2.1 What
   versions do you use ? If you have older versions of these softs, it may not work
   and you should upgrade your configuration… Etienne..
 *  Thread Starter [songsta](https://wordpress.org/support/users/songsta/)
 * (@songsta)
 * [7 years, 11 months ago](https://wordpress.org/support/topic/installation-problem-141/#post-10438603)
 * Hi Etienne
 * Thanks for your quick response!
 * I’m running WordPress 4.9.6 and PHP 7.2.1.
 * The problem with the warnings is that they push the left hand side menu down 
   and then you can’t access most of the menu items.
 * Zayne
 *  Plugin Author [efreja](https://wordpress.org/support/users/efreja/)
 * (@efreja)
 * [7 years, 11 months ago](https://wordpress.org/support/topic/installation-problem-141/#post-10439562)
 * I have the same versions. I deinstalled and resinstalled the plugin without any
   problem.
    The difference probably come from the fact that I wasn’t in wordpress
   debug. You are probably . Why ? Developing youself ? If you modify: define( ‘
   WP_DEBUG’, true ); to define( ‘WP_DEBUG’, false ); in your wp-config.php file,
   the error should disappear. However, I’m going to correct the code so as to get
   rid of these warnings. Etienne.
 *  Plugin Author [efreja](https://wordpress.org/support/users/efreja/)
 * (@efreja)
 * [7 years, 11 months ago](https://wordpress.org/support/topic/installation-problem-141/#post-10439760)
 * Fixed in version 1.0.1

Viewing 4 replies - 1 through 4 (of 4 total)

The topic ‘installation problem’ is closed to new replies.

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 * 4 replies
 * 2 participants
 * Last reply from: [efreja](https://wordpress.org/support/users/efreja/)
 * Last activity: [7 years, 11 months ago](https://wordpress.org/support/topic/installation-problem-141/#post-10439760)
 * Status: resolved