ERPnext will not work after installation

[alkotocom]

Hello, after installation on ERPnext v13 we get server error, how can we fix this or reinstall it?
Thanks Thomas

Traceback (most recent call last):
File "/home/administrator/frappe-bench/apps/frappe/frappe/app.py", line 54, in application
init_request(request)
File "/home/administrator/frappe-bench/apps/frappe/frappe/app.py", line 122, in init_request
frappe.init(site=site, sites_path=_sites_path)
File "/home/administrator/frappe-bench/apps/frappe/frappe/init.py", line 200, in init
setup_module_map()
File "/home/administrator/frappe-bench/apps/frappe/frappe/init.py", line 1107, in setup_module_map
for module in get_module_list(app):
File "/home/administrator/frappe-bench/apps/frappe/frappe/init.py", line 973, in get_module_list
return get_file_items(os.path.join(os.path.dirname(get_module(app_name).file), "modules.txt"))
File "/home/administrator/frappe-bench/apps/frappe/frappe/init.py", line 931, in get_module
return importlib.import_module(modulename)
File "/usr/lib/python3.7/importlib/init.py", line 127, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "", line 1006, in _gcd_import
File "", line 983, in _find_and_load
File "", line 965, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'pagemaster'