pdf template not working odoo

11st Possible Reason
2If your report doesn't have styles try to add some of these parameters
3in Settings > Parameters > System parameters:
4(first open the website in debug mode then go to setting and in technical
5you will find parameters and in side it system parameters)
6
7web.base.url: <IP address>:<Port>
8
9web.base.url.freeze: True. If this parameter is not used then if the 
10administrator log in Odoo the web.base.url parameter is updated with
11the current addres that's in the address bar.
12
13report.url: <IP address>:<Port>. This should be used if web.base.url
14parameter is not enough to make it work. Usually this url should be: 
15http://127.0.0.1:8069
16
17
182nd Possible Reason
19Also it is possible that the package wkhtmltopdf is not well installed 
20or it has not the correct version. Here you can check the release 0.12.5
21that works well with Odoo v10 and later versions.
22
233rd Possible Reason
24As it is suggested here, the report contents must be inside this 
25element with that specific class: <div class="page">
26
27