Thank you for taking the time to report this bug and helping to make Ubuntu better. We will need additional information in order to determine the core problem.
Try to re-install Lubuntu but this time boot into live session instead. When you reach the desktop environment properly, open a terminal (CTRL+ALT+T) and run the following command
ubiquity --debug
The window for the installation should open. Proceed with installation and if it crashes again attach here any logs from that, as separate attachments.
Thank you for taking the time to report this bug and helping to make Ubuntu better. We will need additional information in order to determine the core problem.
Try to re-install Lubuntu but this time boot into live session instead. When you reach the desktop environment properly, open a terminal (CTRL+ALT+T) and run the following command
ubiquity --debug
The window for the installation should open. Proceed with installation and if it crashes again attach here any logs from that, as separate attachments.
Best Regards
NikTh