Hi Nikolka,
Please re-download the fonts WooCommerce –> Booster settings –> PDF invoices –> Advanced –> Fonts Manager –> Actions “Re-download”
If that did not work, please try the following.
1) Download the fonts from here: https://storage.boosterio.bigscoots-staging.com/tcpdf_fonts/fonts.zip
2) And after that, unzip it to this folder:
wp-content\uploads\woocommerce_uploads\wcj_uploads\tcpdf_fonts
We hope this will resolve the issue.
Thanks,
Booster.io Support