Hi

The error appears because wkhtmltopdf is not installed or not detected by Odoo. On Windows, Odoo Community Edition does not include wkhtmltopdf, so you must install it manually. The required version is the patched Qt version 0.12.6, which you can download from the official packaging repository on GitHub. After extracting it, place it in C:\Program Files\wkhtmltopdf\ and make sure the file wkhtmltopdf.exe is inside the bin folder.

Next, you must add the path C:\Program Files\wkhtmltopdf\bin to your Windows system environment variables under Path. After saving and restarting the system (or the Odoo service), you can verify the installation by running wkhtmltopdf --version in a command prompt. Once Odoo detects it, PDF export and report printing will work normally.

Hope it helps