Exception\UnknownExtensionException: The module does not exist or is not installed
I have agree with @4k4 you can fix this with database

If your module have been deleted from the system use this query

delete from `key_value` where collection = 'system.schema' and name = '$extension_name';


for example:

delete from `key_value` where collection = 'system.schema' and name = 'config_tools';
delete from `key_value` where collection = 'system.schema' and name = 'git_config';