Internal Server Error when trying to settle

[vxnxnt]

I run into an "Internal Server Error" each time immediately after pressing the "Register settlement" button. I'm running the project locally in docker and I confirmed this error on a separate instance I quickly spun up and imported from my original instance. I doubled checked that my default currency is set as well.
I would really appreciate the help!

Here are my docker logs:

[2026-04-25 09:31:47 +0000] [1] [INFO] Starting gunicorn 25.1.0
[2026-04-25 09:31:47 +0000] [1] [INFO] Listening at: http://0.0.0.0:8000 (1)
[2026-04-25 09:31:47 +0000] [1] [INFO] Using worker: sync
[2026-04-25 09:31:47 +0000] [1] [INFO] Control socket listening at /gunicorn.ctl
[2026-04-25 09:31:47 +0000] [4] [INFO] Booting worker with pid: 4
/src/ihatemoney/run.py:89: UserWarning: Running a server without changing the SECRET_KEY can lead to user impersonation. Please update your configuration file.
  warnings.warn(
INFO  [alembic.runtime.migration] Context impl SQLiteImpl.
INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
INFO  [alembic.runtime.migration] Running upgrade  -> b9a10d5d63ce, Initial migration
INFO  [alembic.runtime.migration] Running upgrade b9a10d5d63ce -> 26d6a218c329, Add Person.weight column
INFO  [alembic.runtime.migration] Running upgrade 26d6a218c329 -> f629c8ef4ab0, Initialize all members weights to 1
INFO  [alembic.runtime.migration] Running upgrade f629c8ef4ab0 -> b78f8a8bdb16, hash project passwords
INFO  [alembic.runtime.migration] Running upgrade b78f8a8bdb16 -> afbf27e6ef20, add bill.import_date field
INFO  [alembic.runtime.migration] Running upgrade afbf27e6ef20 -> a67119aa3ee5, Migrate negative weights
INFO  [alembic.runtime.migration] Running upgrade a67119aa3ee5 -> 6c6fb2b7f229, empty message
INFO  [alembic.runtime.migration] Running upgrade 6c6fb2b7f229 -> 2dcb0c0048dc, autologger
INFO  [alembic.runtime.migration] Running upgrade 2dcb0c0048dc -> cb038f79982e, sqlite_autoincrement
INFO  [alembic.runtime.migration] Running upgrade cb038f79982e -> 927ed575acbd, Add currencies
INFO  [alembic.runtime.migration] Running upgrade 927ed575acbd -> 7a9b38559992, new bill type attribute added
INFO  [alembic.runtime.migration] Running wrapper 7a9b38559992 -> 06884b17c50f, fix password hash length
/src/ihatemoney/currency_convertor.py:30: UserWarning: Call to https://api.exchangerate.host/latest?base=USD failed: KeyError: 'rates'
  warnings.warn(
ERROR [ihatemoney.run] Exception on /test/settle [POST]
Traceback (most recent call last):
  File "/usr/local/lib/python3.11/site-packages/flask/app.py", line 1511, in wsgi_app
    response = self.full_dispatch_request()
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/flask/app.py", line 919, in full_dispatch_request
    rv = self.handle_user_exception(e)
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/flask_restful/__init__.py", line 298, in error_router
    return original_handler(e)
           ^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/flask/app.py", line 917, in full_dispatch_request
    rv = self.dispatch_request()
         ^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/flask/app.py", line 902, in dispatch_request
    return self.ensure_sync(self.view_functions[rule.endpoint])(**view_args)  # type: ignore[no-any-return]
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/src/ihatemoney/web.py", line 885, in add_settlement_bill
    settlement = Bill(
                 ^^^^^
  File "<string>", line 4, in __init__
  File "/usr/local/lib/python3.11/site-packages/sqlalchemy/orm/state.py", line 596, in _initialize_instance
    with util.safe_reraise():
  File "/usr/local/lib/python3.11/site-packages/sqlalchemy/util/langhelpers.py", line 121, in __exit__
    raise exc_value.with_traceback(exc_tb)
  File "/usr/local/lib/python3.11/site-packages/sqlalchemy/orm/state.py", line 594, in _initialize_instance
    manager.original_init(*mixed[1:], **kwargs)
  File "/src/ihatemoney/models.py", line 747, in __init__
    self.converted_amount = self.currency_helper.exchange_currency(
                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/src/ihatemoney/currency_convertor.py", line 224, in exchange_currency
    source_rate = rates[source_currency]
                  ~~~~~^^^^^^^^^^^^^^^^^
KeyError: ''

[zorun]

Do you have bills in different currencies in your project? We don't support this anymore, but I'm a bit surprised it breaks this way.

Note that currency support will be completely dropped at some point, see #1232

[vxnxnt]

Thanks for responding. I double checked the UI and the exported json, but all entries (as well as the project's default currency) consistently only have EUR listed as the currency.