Currency formatting is not possible using the 'C' locale

[tango.sierra]

Bonjour,

Je travaille à mettre en production une instance de crème en version 2.1.3 sur un serveur Ubuntu 18 avec Python 3.6.9 et Apache/modWSGI.
Tout fonctionne bien sauf quand j'essaie de rajouter une facture, je me retrouve avec une erreur 500.

Code :

LANG=fr_FR.UTF-8
LANGUAGE=
LC_CTYPE="fr_FR.UTF-8"
LC_NUMERIC="fr_FR.UTF-8"
LC_TIME="fr_FR.UTF-8"
LC_COLLATE="fr_FR.UTF-8"
LC_MONETARY="fr_FR.UTF-8"
LC_MESSAGES="fr_FR.UTF-8"
LC_PAPER="fr_FR.UTF-8"
LC_NAME="fr_FR.UTF-8"
LC_ADDRESS="fr_FR.UTF-8"
LC_TELEPHONE="fr_FR.UTF-8"
LC_MEASUREMENT="fr_FR.UTF-8"
LC_IDENTIFICATION="fr_FR.UTF-8"
LC_ALL=

Voici l'erreur que j'ai dans les logs =>

Code :

ERROR - django.request : Internal Server Error: /billing/invoice/22
Traceback (most recent call last):
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/core/handlers/exception.py", line 34, in inner
    response = get_response(request)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/core/handlers/base.py", line 145, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/core/handlers/base.py", line 143, in _get_response
    response = response.render()
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/response.py", line 106, in render
    self.content = self.rendered_content
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/response.py", line 83, in rendered_content
    content = template.render(context, self._request)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/backends/django.py", line 61, in render
    return self.template.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 171, in render
    return self._render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 163, in _render
    return self.nodelist.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/loader_tags.py", line 150, in render
    return compiled_parent._render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 163, in _render
    return self.nodelist.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/loader_tags.py", line 150, in render
    return compiled_parent._render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 163, in _render
    return self.nodelist.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/loader_tags.py", line 150, in render
    return compiled_parent._render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 163, in _render
    return self.nodelist.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/loader_tags.py", line 150, in render
    return compiled_parent._render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 163, in _render
    return self.nodelist.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/loader_tags.py", line 62, in render
    result = block.nodelist.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/defaulttags.py", line 398, in render
    return strip_spaces_between_tags(self.nodelist.render(context).strip())
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/loader_tags.py", line 62, in render
    result = block.nodelist.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/library.py", line 192, in render
    output = self.func(*resolved_args, **resolved_kwargs)
  File "/srv/creme_crm-2.1/creme/creme_core/templatetags/creme_bricks.py", line 923, in brick_display
    for brick in bricks_to_render
  File "/srv/creme_crm-2.1/creme/creme_core/templatetags/creme_bricks.py", line 923, in <genexpr>
    for brick in bricks_to_render
  File "/srv/creme_crm-2.1/creme/creme_core/views/bricks.py", line 68, in render_detailview_brick
    return fun(context)
  File "/srv/creme_crm-2.1/creme/billing/bricks.py", line 129, in detailview_display
    related_item_label=self.related_item_label,
  File "/srv/creme_crm-2.1/creme/creme_core/gui/bricks.py", line 156, in _render
    return get_template(self.template_name).render(template_context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/backends/django.py", line 61, in render
    return self.template.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 171, in render
    return self._render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 163, in _render
    return self.nodelist.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/loader_tags.py", line 150, in render
    return compiled_parent._render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 163, in _render
    return self.nodelist.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/loader_tags.py", line 150, in render
    return compiled_parent._render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 163, in _render
    return self.nodelist.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/loader_tags.py", line 62, in render
    result = block.nodelist.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/defaulttags.py", line 309, in render
    return nodelist.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/defaulttags.py", line 513, in render
    return self.nodelist.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/loader_tags.py", line 188, in render
    return template.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 173, in render
    return self._render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 163, in _render
    return self.nodelist.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/defaulttags.py", line 513, in render
    return self.nodelist.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/defaulttags.py", line 513, in render
    return self.nodelist.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/defaulttags.py", line 309, in render
    return nodelist.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 937, in render
    bit = node.render_annotated(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 904, in render_annotated
    return self.render(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 987, in render
    output = self.filter_expression.resolve(context)
  File "/home/user/.virtualenvs/creme_2_1/lib/python3.6/site-packages/django/template/base.py", line 698, in resolve
    new_obj = func(obj, *arg_vals)
  File "/srv/creme_crm-2.1/creme/creme_core/templatetags/creme_core_tags.py", line 324, in format_amount
    return currency(amount, currency_or_id)
  File "/srv/creme_crm-2.1/creme/creme_core/utils/currency_format.py", line 103, in currency
    raise ValueError("Currency formatting is not possible using the 'C' locale.")
ValueError: Currency formatting is not possible using the 'C' locale.

J'ai vu qu'une personne avait eu plus ou moins le même problème ICI, mais pas avec le même fichier, du coup, je préfère venir chercher de l'aide ici avant d'essayer de modifier quoi que ce soit.

Je vous remercie par avance.