自从Django 1.8迁移到2.1以来，我经常会遇到数据库迁移错误。它不会直接在迁移过程中发生，而是在调用manage.py时出现：
django.db.utils.ProgrammingError: relation "obj1_obj2" does not exist
LINE 1: ....
迁移甚至还没有开始，但是它定义了关系或引起错误的任何模型更改。
在本地工作时，我通常回滚代码，然后进行迁移，但是在云提供商上，这是无用的解决方案。我在python 3.6上工作
完整追溯：
Traceback (most recent call last):
File "./manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "/app/.heroku/python/lib/python3.6/site-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
utility.execute()
File "/app/.heroku/python/lib/python3.6/site-packages/django/core/management/__init__.py", line 375, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/app/.heroku/python/lib/python3.6/site-packages/django/core/management/base.py", line 316, in run_from_argv
self.execute(*args, **cmd_options)
File "/app/.heroku/python/lib/python3.6/site-packages/django/core/management/base.py", line 350, in execute
self.check()
File "/app/.heroku/python/lib/python3.6/site-packages/django/core/management/base.py", line 379, in check
include_deployment_checks=include_deployment_checks,
File "/app/.heroku/python/lib/python3.6/site-packages/django/core/management/commands/migrate.py", line 60, in _run_checks
issues.extend(super()._run_checks(**kwargs))
File "/app/.heroku/python/lib/python3.6/site-packages/django/core/management/base.py", line 366, in _run_checks
return checks.run_checks(**kwargs)
File "/app/.heroku/python/lib/python3.6/site-packages/django/core/checks/registry.py", line 71, in run_checks
new_errors = check(app_configs=app_configs)
File "/app/.heroku/python/lib/python3.6/site-packages/django/core/checks/urls.py", line 13, in check_url_config
return check_resolver(resolver)
File "/app/.heroku/python/lib/python3.6/site-packages/django/core/checks/urls.py", line 23, in check_resolver
return check_method()
File "/app/.heroku/python/lib/python3.6/site-packages/django/urls/resolvers.py", line 396, in check
for pattern in self.url_patterns:
File "/app/.heroku/python/lib/python3.6/site-packages/django/utils/functional.py", line 37, in __get__
res = instance.__dict__[self.name] = self.func(instance)
File "/app/.heroku/python/lib/python3.6/site-packages/django/urls/resolvers.py", line 533, in url_patterns
patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
File "/app/.heroku/python/lib/python3.6/site-packages/django/utils/functional.py", line 37, in __get__
res = instance.__dict__[self.name] = self.func(instance)
File "/app/.heroku/python/lib/python3.6/site-packages/django/urls/resolvers.py", line 526, in urlconf_module
return import_module(self.urlconf_name)
File "/app/.heroku/python/lib/python3.6/importlib/__init__.py", line 126, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 994, in _gcd_import
File "<frozen importlib._bootstrap>", line 971, in _find_and_load
File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
File "<frozen importlib._bootstrap_external>", line 678, in exec_module
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "/app/aliz/urls.py", line 8, in <module>
from camps.urls import api_urlpatterns as camps_api_urlpatterns
File "/app/camps/urls.py", line 31, in <module>
path('obecne/', staff_member_required(CurrentEventDetailView.as_view()), {'e_pk': Event.objects.filter(current=True).first().pk}, name='current_camps'),
File "/app/.heroku/python/lib/python3.6/site-packages/django/db/models/query.py", line 605, in first
for obj in (self if self.ordered else self.order_by('pk'))[:1]:
File "/app/.heroku/python/lib/python3.6/site-packages/django/db/models/query.py", line 268, in __iter__
self._fetch_all()
File "/app/.heroku/python/lib/python3.6/site-packages/django/db/models/query.py", line 1186, in _fetch_all
self._result_cache = list(self._iterable_class(self))
File "/app/.heroku/python/lib/python3.6/site-packages/django/db/models/query.py", line 54, in __iter__
results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size)
File "/app/.heroku/python/lib/python3.6/site-packages/django/db/models/sql/compiler.py", line 1065, in execute_sql
cursor.execute(sql, params)
File "/app/.heroku/python/lib/python3.6/site-packages/django/db/backends/utils.py", line 68, in execute
return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
File "/app/.heroku/python/lib/python3.6/site-packages/django/db/backends/utils.py", line 77, in _execute_with_wrappers
return executor(sql, params, many, context)
File "/app/.heroku/python/lib/python3.6/site-packages/django/db/backends/utils.py", line 85, in _execute
return self.cursor.execute(sql, params)
File "/app/.heroku/python/lib/python3.6/site-packages/django/db/utils.py", line 89, in __exit__
raise dj_exc_value.with_traceback(traceback) from exc_value