When try to change module name, it shows blank display

I installed a new instance and it work fine but when I try to change the theme it broke down and come with the broken theme. but somehow I fixed it. But when I try to change the module name it is not working showing a blank screen. There are no sugar logs as well.

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The file permissions are right as well.
sudo chmod -R 755 .

sudo chmod -R 775 cache custom modules themes data upload config_override.php

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My version 7.12.3

I have recorded the process: https://nimb.ws/w3yUX9

Any advice would be appreciated. Regards

sudo chown -R www-data:www-data .
sudo chmod -R 755 .
sudo chmod -R 775 cache custom modules themes data upload
sudo chmod 775 config_override.php 2>/dev/null

That www-data needs to be replaced by the actual system user that your web server runs under. This varies depending on your operating system.