Internal Trac Error: IndexError: list index out of range

[anonymous]

When I close a ticket with an entry on "blocked by" I get the following error:

Trac detected an internal error:

IndexError: list index out of range

Python Traceback:

File "build/bdist.linux-x86_64/egg/trac/web/main.py", line 513, in _dispatch_request
  dispatcher.dispatch(req)
File "build/bdist.linux-x86_64/egg/trac/web/main.py", line 222, in dispatch
  resp = chosen_handler.process_request(req)
File "build/bdist.linux-x86_64/egg/trac/ticket/web_ui.py", line 182, in process_request
  return self._process_ticket_request(req)
File "build/bdist.linux-x86_64/egg/trac/ticket/web_ui.py", line 619, in _process_ticket_request
  self._do_save(req, ticket, action)
File "build/bdist.linux-x86_64/egg/trac/ticket/web_ui.py", line 1342, in _do_save
  replyto=req.args.get('replyto'))
File "build/bdist.linux-x86_64/egg/trac/ticket/model.py", line 369, in save_changes
  listener.ticket_changed(self, comment, author, old_values)
File "build/bdist.linux-x86_64/egg/mastertickets/api.py", line 119, in ticket_changed
  links.save(author, comment, tkt.time_changed, db)
File "build/bdist.linux-x86_64/egg/mastertickets/model.py", line 75, in save
  """, (n, field))[0][0]

System Information:

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:37.0) Gecko/20100101 Firefox/37.0
Trac 	1.0.5
Genshi 	0.7 (with speedups)
pysqlite 	2.6.0
Python 	2.7.6 (default, Nov 21 2013, 15:55:38) [GCC]
RPC 	1.1.2
setuptools 	12.3
SQLite 	3.7.17
jQuery	1.7.2
jQuery UI	1.8.21
jQuery Timepicker	1.0.1

[Jun Omae]

#12378 was closed as a duplicate.

[Ryan J Ollos]

In 14695:

4.0.0dev: Fix IndexError when adding blocking or blockedby relation.

The issue was seen when adding a relation to tickets created before, and not updated since, the [ticket-custom] entries for MasterTicketsPlugin were added. Tickets created before the MasterTicketsPlugin was installed won't have entries in the ticket_custom table for blocking and blockedby. Fixes #12303.