Gnucash thinks data file is read-only, how to open it for writing?

[Ben Finney]

John Ralls <jralls at ceridwen.us> writes:

> Don't forget to look at /tmp (or maybe /usr/tmp)/gnucash.trace to see it 
> there are any relevant error messages.

That file contains only:

=====
* 11:06:33  CRIT <gnc.gui> gnc_tree_model_budget_get_iter_for_budget: assertion `GNC_BUDGET(bgt)' failed
* 11:07:07  CRIT <gnc.gui> gnc_tree_model_budget_get_iter_for_budget: assertion `GNC_BUDGET(bgt)' failed
=====

There is no date on the timestamp (makes for ambiguous log entries, to
say the least!).

But the file's timestamp coincides with the most recent run of Gnucash.

-- 
 \             “Experience is that marvelous thing that enables you to |
  `\   recognize a mistake when you make it again.” —Franklin P. Jones |
_o__)                                                                  |
Ben Finney