Created attachment 373471 [details]
tracefile

Repro:

1. have an uncommitted edit to a transaction
2. attempt to open a different file (I used the recently-used list)
3. warning pops about the unsaved transaction - choose cancel
4. same warning pops again - cancel again
5. gnucash hangs (was on an account window, that window blanked all cells except for the new transaction date, probably where the cursor already was)
6. crashes after ~1 min
7. on restart, it complains about being unable to obtain lock on the *newly opened* file
8. lock on initial file is released
9. uncommitted edit is discarded

stderr:
sys:1: Warning: g_object_ref: assertion 'G_IS_OBJECT (object)' failed
sys:1: Warning: g_object_freeze_notify: assertion 'G_IS_OBJECT (object)' failed
sys:1: Warning: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
sys:1: Warning: g_object_notify: assertion 'G_IS_OBJECT (object)' failed
sys:1: Warning: g_object_thaw_notify: assertion 'G_IS_OBJECT (object)' failed
Segmentation fault (core dumped)

Perversely, one run of gnucash --debug produced only segfault message on crash. Above stderr results from both plain gnucash and --debug.

On multiple repros, the duration of hang varies widely - one run managed to fully open the new file up through showing a valid Accounts window before crashing a few seconds later (that trace is attached).

Related:
1. for extra fun, attempt to open the exact same file - after the double cancel there is no hang/crash
2. on one run, the offending account window is reopened, with zero transactions
3. this is not data corruption, only the window display (reopening the account from Accounts shows no data loss)

stderr:
sys:1: Warning: g_hash_table_lookup: assertion 'hash_table != NULL' failed
sys:1: Warning: g_hash_table_insert_internal: assertion 'hash_table != NULL' failed

Trace attached of a crashing run. Timestamp on my terminal post-crash is 02:12:23