Permission error plus I/O error exporting item list to excel

I got following error when I try to export item list to excel

Traceback (most recent call last):
File “/opt/bitnami/apps/erpnext/htdocs/frappe-bench/apps/frappe/frappe/app.py”, line 67, in application
response = frappe.api.handle()
File “/opt/bitnami/apps/erpnext/htdocs/frappe-bench/apps/frappe/frappe/api.py”, line 53, in handle
return frappe.handler.handle()
File “/opt/bitnami/apps/erpnext/htdocs/frappe-bench/apps/frappe/frappe/handler.py”, line 22, in handle
data = execute_cmd(cmd)
File “/opt/bitnami/apps/erpnext/htdocs/frappe-bench/apps/frappe/frappe/handler.py”, line 53, in execute_cmd
return frappe.call(method, **frappe.form_dict)
File “/opt/bitnami/apps/erpnext/htdocs/frappe-bench/apps/frappe/frappe/init.py”, line 939, in call
return fn(*args, **newargs)
File “/opt/bitnami/apps/erpnext/htdocs/frappe-bench/apps/frappe/frappe/core/doctype/data_import/exporter.py”, line 289, in get_template
with open(filename, ‘wb’) as f:
IOError: [Errno 13] Permission denied: ‘1c0a8e395d’