ModuleNotFoundError: No module named 'pdfkit'

When I was trying to run odoo server it was returning internal server error so I checked the log file and I found this error

ModuleNotFoundError: No module named 'pdfkit'

so to fix it install pdfkit by running the command bellow

sudo pip3 install pdfkit

odoo server wide modules

Odoo server wide modules are modules are supposed to provide features not necessarily tied to a particular database and they are loaded after running the server just as base and web modules , we can use this feature for example if we want to create login API with HTTP type , or API to return the databases list ...etc

How to define custom module as server wide module ?

First : if we are running the server from command line directly we must use --load with the running command 

eg : ./odoo-bin --addons-path='/opt/test/odoo-14.0/addons' --load=base,web,custom_web

Second : if we add odoo as service and created configuration file we can add server_wide_modules inside the configuration file 

eg :
[options]
; This is the password that allows database operations:
admin_passwd = master_admin@ssc
db_host = False
server_wide_modules = base,web,custom_web
db_port = False
db_user = test
db_password = False
addons_path = /opt/test/odoo/addons
logfile = /var/log/test/odoo-test.log
http_port = 8080
limit_request = 8192
limit_time_cpu = 600
limit_time_real = 120000