Unable to install/remove the plugin/theme for the WordPress instance: An error has occurred when decoding JSON by Zend_Json: Illegal Token

Ivan Kamnev

Updated January 14, 2021 11:42

kb: bug ext: wptk ABT: Group A Plesk Obsidian for Linux

Applicable to:

Unable to install/remove the plugin/theme in Plesk > example.com > WordPress, the process fails with the error below:

CONFIG_TEXT: An error has occurred when decoding JSON by Zend_Json: Illegal Token
Failed to reset cache for the instance #74, reason: An error has occurred when decoding
JSON: Illegal Token
The same error can be sent to the administrator of the WordPress instance.
There is a Byte-Order Mark (BOM) character in one of the WordPress files with .php extension.

Product issue:

#EXTWPTOOLK-4736 "Update of certain plugins & themes will not mark WordPress sites as broken if there were JSON decoding errors."
Fixed in:
- WordPress Toolkit 4.8.4 29 June 2020

Please consider updating WordPress Toolkit extension:

If an update is not possible for some reason, apply the workaround below:

Temporary solution

Log into the serer via SSH.
Execute the command below to find .php files with the BOM character:

# grep -rlI $'\xEF\xBB\xBF' /var/www/vhosts/example.com/httpdocs | grep -i .php$

/var/www/vhosts/example.com/httpdocs/wp-content/plugins/vc-google-maps/vc_extend.php
Create a backup of the found file from the step №2:

# cp -a /var/www/vhosts/example.com/httpdocs/wp-content/plugins/vc-google-maps/vc_extend.php{,.bkp}
Run the command below to remove BOM character from the affected WordPress file:

# sed -i '1 s/^\xef\xbb\xbf//' var/www/vhosts/example.com/httpdocs/wp-content/plugins/vc-google-maps/vc_extend.php