Customize - problem with link-field of issue

Hallo, the goal is, to make invoices from issues.

Because of that, i want to customize the “timesheet” and add a new row.
I made a link - the field options i filled with “customer”.
But i get a mesasage, if i click in this new field:

Please type some additional information that could help us reproduce this issue:
App Versions

{
“erpnext”: “8.3.6”,
“frappe”: “8.3.10”,
“quintact”: “0.0.1”
}

Route

Form/Timesheet/New Timesheet 4

Error Report

Traceback (most recent call last):
File “/opt/erpnext5/frappe-bench/apps/frappe/frappe/app.py”, line 56, in application
response = frappe.handler.handle()
File “/opt/erpnext5/frappe-bench/apps/frappe/frappe/handler.py”, line 21, in handle
data = execute_cmd(cmd)
File “/opt/erpnext5/frappe-bench/apps/frappe/frappe/handler.py”, line 52, in execute_cmd
return frappe.call(method, **frappe.form_dict)
File “/opt/erpnext5/frappe-bench/apps/frappe/frappe/init.py”, line 913, in call
return fn(*args, **newargs)
File “/opt/erpnext5/frappe-bench/apps/frappe/frappe/desk/search.py”, line 13, in search_link
search_widget(doctype, txt, query, searchfield=searchfield, page_length=page_length, filters=filters)
File “/opt/erpnext5/frappe-bench/apps/frappe/frappe/desk/search.py”, line 101, in search_widget
as_list=not as_dict)
File “/opt/erpnext5/frappe-bench/apps/frappe/frappe/init.py”, line 1119, in get_list
return frappe.model.db_query.DatabaseQuery(doctype).execute(None, *args, **kwargs)
File “/opt/erpnext5/frappe-bench/apps/frappe/frappe/model/db_query.py”, line 88, in execute
result = self.build_and_run()
File “/opt/erpnext5/frappe-bench/apps/frappe/frappe/model/db_query.py”, line 100, in build_and_run
args = self.prepare_args()
File “/opt/erpnext5/frappe-bench/apps/frappe/frappe/model/db_query.py”, line 117, in prepare_args
self.set_optional_columns()
File “/opt/erpnext5/frappe-bench/apps/frappe/frappe/model/db_query.py”, line 218, in set_optional_columns
columns = frappe.db.get_table_columns(self.doctype)
File “/opt/erpnext5/frappe-bench/apps/frappe/frappe/database.py”, line 823, in get_table_columns
return self.get_db_table_columns(‘tab’ + doctype)
File “/opt/erpnext5/frappe-bench/apps/frappe/frappe/database.py”, line 819, in get_db_table_columns
return [r[0] for r in self.sql(“DESC %s” % table)]
File “/opt/erpnext5/frappe-bench/apps/frappe/frappe/database.py”, line 153, in sql
self._cursor.execute(query)
File “/opt/erpnext5/frappe-bench/env/local/lib/python2.7/site-packages/MySQLdb/cursors.py”, line 250, in execute
self.errorhandler(self, exc, value)
File “/opt/erpnext5/frappe-bench/env/local/lib/python2.7/site-packages/MySQLdb/connections.py”, line 50, in defaulterrorhandler
raise errorvalue
ProgrammingError: (1146, “Table ‘374de01624dfb7d8.tabcustomer’ doesn’t exist”)

Request Data

{
“type”: “GET”,
“args”: {
“txt”: “”,
“doctype”: “customer”,
“cmd”: “frappe.desk.search.search_link”
},
“url”: “/”
}

Response JSON

{}

Any ideas what is wrong with that?
Thanks a lot.

It seems you have mentioned option wrongly for custom field customer.

The field options should have Customer - the ‘C’ being capital. DocType names are case sensitive, with which they also have their table names defined.

Hallo, yes, i took both versions - but i think i had often to reload the site in frondend, it works.

That is actually a problem, i have often the problem, that i have to reload the site manually (F5) to see the complete status.
Bug or feature? (Firefox 54.0.1

thanks a lot for your quick response. Have a good day.