Django stops working with RuntimeError: populate() isn't reentrant

Django stops working with RuntimeError: populate() isn't reentrant

I've been developing a Django web application deployed on an Apache server with WSGI, and everything has been going smoothly. Today, I made some minor changes to my app's admin.py in an attempt to customize the build-in Django Admin interface, and initially made a syntax error (an unclosed parenthesis). This meant that when I touched wsgi.py and loaded the code (I have WSGI running in daemon mode on my virtual host), my website was replaced with an Internal Server Error because WSGI stopped when it hit the syntax error.

admin.py

wsgi.py

So I fixed the syntax error, checked that I didn't have any more with manage.py check, and touched wsgi.py to redeploy. But my website still displays an Internal Server Error! Checking the Apache logs, this is what I see:

manage.py check

wsgi.py

[Sun Nov 23 13:52:46 2014] [info] mod_wsgi (pid=19093): Create interpreter 'quotes.cs.cornell.edu|'. [Sun Nov 23 13:52:46 2014] [info] mod_wsgi (pid=19093): Adding '/extra/www/html/quotes/quotes_django' to path. [Sun Nov 23 13:52:46 2014] [info] mod_wsgi (pid=19093): Adding '/opt/rh/python27/root/usr/lib64/python2.7/site- packages/' to path. [Sun Nov 23 13:52:46 2014] [info] [client 128.84.33.19] mod_wsgi (pid=19093, process='quotes.cs.cornell.edu', application='quotes.cs.cornell.edu|'): Loading WSGI script '/extra/www/html/quotes/quotes_django/quotes_django/ wsgi.py'. [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] mod_wsgi (pid=19093): Target WSGI script '/extra/www/html/ quotes/quotes_django/quotes_django/wsgi.py' cannot be loaded as Python module. [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] mod_wsgi (pid=19093): Exception occurred processing WSGI script '/extra/www/html/quotes/quotes_django/quotes_django/wsgi.py'. [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] Traceback (most recent call last): [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] File "/extra/www/html/quotes/quotes_django/ quotes_django/wsgi.py", line 14, in <module> [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] application = get_wsgi_application() [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] File "/opt/rh/python27/root/usr/lib64/python2.7/site- packages/django/core/wsgi.py", line 14, in get_wsgi_application [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] django.setup() [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] File "/opt/rh/python27/root/usr/lib64/python2.7/site- packages/django/__init__.py", line 21, in setup [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] apps.populate(settings.INSTALLED_APPS) [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] File "/opt/rh/python27/root/usr/lib64/python2.7/site- packages/django/apps/registry.py", line 115, in populate [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] app_config.ready() [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] File "/opt/rh/python27/root/usr/lib64/python2.7/site- packages/django/contrib/admin/apps.py", line 22, in ready [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] self.module.autodiscover() [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] File "/opt/rh/python27/root/usr/lib64/python2.7/site- packages/django/contrib/admin/__init__.py", line 23, in autodiscover [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] autodiscover_modules('admin', register_to=site) [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] File "/opt/rh/python27/root/usr/lib64/python2.7/site- packages/django/utils/module_loading.py", line 74, in autodiscover_modules [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] import_module('%s.%s' % (app_config.name, module_to_search)) [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] File "/usr/lib64/python2.7/importlib/__init__.py", line 37, in import_module [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] __import__(name) [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] File "/extra/www/html/quotes/quotes_django/quotespage/ admin.py", line 25 [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] approve_quotes.short_description = "Approve selected quotes" [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] ^ [Sun Nov 23 13:52:46 2014] [error] [client 128.84.33.19] SyntaxError: invalid syntax [Sun Nov 23 13:53:36 2014] [info] [client 128.84.33.19] mod_wsgi (pid=19093, process='quotes.cs.cornell.edu', application='quotes.cs.cornell.edu|'): Loading WSGI script '/extra/www/html/quotes/quotes_django/quotes_django/ wsgi.py'. [Sun Nov 23 13:53:36 2014] [error] [client 128.84.33.19] mod_wsgi (pid=19093): Target WSGI script '/extra/www/html/ quotes/quotes_django/quotes_django/wsgi.py' cannot be loaded as Python module. [Sun Nov 23 13:53:36 2014] [error] [client 128.84.33.19] mod_wsgi (pid=19093): Exception occurred processing WSGI script '/extra/www/html/quotes/quotes_django/quotes_django/wsgi.py'. [Sun Nov 23 13:53:36 2014] [error] [client 128.84.33.19] Traceback (most recent call last): [Sun Nov 23 13:53:36 2014] [error] [client 128.84.33.19] File "/extra/www/html/quotes/quotes_django/ quotes_django/wsgi.py", line 14, in <module> [Sun Nov 23 13:53:36 2014] [error] [client 128.84.33.19] application = get_wsgi_application() [Sun Nov 23 13:53:36 2014] [error] [client 128.84.33.19] File "/opt/rh/python27/root/usr/lib64/python2.7/site- packages/django/core/wsgi.py", line 14, in get_wsgi_application [Sun Nov 23 13:53:36 2014] [error] [client 128.84.33.19] django.setup() [Sun Nov 23 13:53:36 2014] [error] [client 128.84.33.19] File "/opt/rh/python27/root/usr/lib64/python2.7/site- packages/django/__init__.py", line 21, in setup [Sun Nov 23 13:53:36 2014] [error] [client 128.84.33.19] apps.populate(settings.INSTALLED_APPS) [Sun Nov 23 13:53:36 2014] [error] [client 128.84.33.19] File "/opt/rh/python27/root/usr/lib64/python2.7/site- packages/django/apps/registry.py", line 78, in populate [Sun Nov 23 13:53:36 2014] [error] [client 128.84.33.19] raise RuntimeError("populate() isn't reentrant") [Sun Nov 23 13:53:36 2014] [error] [client 128.84.33.19] RuntimeError: populate() isn't reentrant

The first series of errors shows WSGI failing due to the syntax error in my admin.py. However, the second series of errors seems to show an error internal to Django:

admin.py

RuntimeError: populate() isn't reentrant

thrown from the populate method of registry.py.

populate

registry.py

Googling this error message returns surprisingly little information, none of it from Django documentation. Apparently, it can sometimes happen if you name an app twice in your settings.py, but I'm not doing that. More importantly, I haven't changed settings.py since the point where the website was working fine -- the only thing I changed was admin.py.

settings.py

admin.py

I tried reverting all the changes I made, so all my Python code is back in the state it was when the website was working -- and I still get the populate() isn't reentrant error when I try to make WSGI reload the code!

populate() isn't reentrant

I've also tried commenting-out different apps in the INSTALLED_APPS section of settings.py, and even with only 'django.contrib.staticfiles' enabled the error still happens. Weirdly, I still get the error even if I comment out all the apps -- Django throws the error even when it isn't loading any apps!

settings.py

Does anyone know what's going on here? Or any better way for me to debug this error, since the traceback in the Apache log is pretty unhelpful?

Notes: I'm using Django 1.7, Apache 2.2, and Python 2.7.

I'd try removing all .pyc files that might be around.
– dukebody
Nov 23 '14 at 20:24

Nope, removing all .pyc files didn't help. Touching wsgi.py results in the same Apache error, and the .pyc files aren't recreated.
– Edward
Nov 23 '14 at 20:28

wsgi.py

Have you tried restarting Apache?
– dukebody
Nov 23 '14 at 20:29

I can't restart Apache because I don't have the rights to on this server. The administrator with root access won't be back in the office until Monday.
– Edward
Nov 23 '14 at 20:32

In my case it was not installed app from INSTALLED_APPS in environment.
– maciek
Aug 19 '15 at 11:23

25 Answers
25

My server's administrator restarted Apache, and that magically fixed this problem. The exact same Python files loaded without causing populate() isn't reentrant. I even tried loading another file with a syntax error, then fixing it, and the server was able to load the new file and run correctly with no problems.

populate() isn't reentrant

I still don't know what was going wrong, but I'm marking this as answered since the problem is gone. (Well, I'll mark it as answered as soon as StackOverflow allows me to accept my own answer.)

Update: After continuing to get this error when I accidentally upload Python with syntax errors, I figured out a workaround that's easier than restarting Apache. When WSGI starts throwing the populate() isn't reentrant error, I replace my Django project's wsgi.py with this simple function:

populate() isn't reentrant

wsgi.py

def application(environ, start_response): if environ['mod_wsgi.process_group'] != '': import signal os.kill(os.getpid(), signal.SIGINT) return ["killed"]

Then I reload my website, and the WSGI daemon process restarts (which I can tell by looking at the Apache log, even though the website still displays the same 500 error).

If I then change wsgi.py back to normal and reload again, WSGI successfully picks up my code without throwing populate() isn't reentrant (assuming I have no syntax errors this time). So the entirety of Apache doesn't need to restart, just the WSGI process, and I can do that without root privileges.

wsgi.py

populate() isn't reentrant

For me the problem was not migrating changes I had made to a model in one of my apps.
– user2662692
Aug 12 '15 at 17:40

Ok, I am facing almost the same problem and yes it gets fixed on rebooting the machine and restarting the server. But the problem keeps repeating. Sometimes all of a sudden. within a month it has occured thrice. If anybody has any idea, please help.
– Rohit
Apr 4 '16 at 16:05

@Rohit, if you want help with your situation, you should probably post a new question describing it. You're unlikely to get an answer in the comments here.
– Edward
Apr 4 '16 at 16:23

There is a startup-timeout option for daemon mode of mod_wsgi in more recent versions of mod_wsgi which assists in recovering from transient errors when Django is being initialised, such as a database not being available. The timeout will cause the process to be automatically restarted if WSGI application doesn't load properly after the timeout period. Even that will not help where you have a permanent issue with your own code. In that case, look for the very first error, not the populate() error as it will give the real reason your code fails.
– Graham Dumpleton
Oct 16 '16 at 0:52

startup-timeout

populate()

For me was just a server restart. Boom! It worked!
– nik_m
Feb 28 '17 at 15:48

I know this is an old answer but I will contribute with my solution:

As a way to diagnose the source of the problem run manage.py checkand see if you find anything there

manage.py check

In my case an outdated requirement was the issue and django was failing to import a submodule

Make sure that your requirements are up to date

I get Error 500 on Apache and I can't found the problem. By this command manage.py check I found the problem. Thank you.
– Ali Hesari
Sep 13 '17 at 22:17

manage.py check

If you're getting this error when using Google App Engine check your logs for other errors which might be causing this. I was getting:

ImproperlyConfigured: Error loading either pysqlite2 or sqlite3 modules (tried in that order): No module named _sqlite3

You can't use SQLite with Google App Engine so commenting out the DATABASES section of settings.py stopped that error and the RuntimeError("populate() isn't reentrant") error as well.

DATABASES

settings.py

RuntimeError("populate() isn't reentrant")

This explains why everything worked fine locally but got 500 error when deployed to GAE. A small hint: searching text "raise" on GAE log page generated exact one hit which led to the error message pointed out by donturner. His solution saved my day :-)
– Donald
Feb 1 at 13:36

It's not a response but a reflexion.

When you upgrade to django 1.7 and you have a 500 error and reload your page, Apache says "populate() isn't reentrant".
I think it's when you load your page, Apache load all the modules you need for your app and when the error is handle it doesn't unload module. So, when you reload your page, apache load again theses modules but it's already loaded. So, apache says "populate() isn't reentrant".

I've two actions to correct this : Restart apache, or correct the error that handle the first 5OO error.

I hope it will help you.

You may be able to fix it without restarting Apache by touching a file (other than wsgi.py) that is early on in the loading process. For example, your settings file:

$ touch settings.py

I haven't properly solved this either, but more info in my question here: Code change monitoring malfunctioning with Django 1.7 on mod-wsgi

This looks like a nice collection of valid responses for the same Apache mod-wsgi error, each guy posting the one that works for him/her, so here is mine:

Do not forget to update your project requirements after deploying :)

Apache stores the wsgi file in its cache.
Disable Apache caching of python files

So first delete the wsgi file and restart your acpache and then add wsgi file again and restart the apache.

I experienced this same problem, and the source of the error for me was just a syntax error in a file I was working with. After fixing the typo, the populate() is not reentrant error disappeared.

populate() is not reentrant

If you are running django from a wsgi script, you might be able to identify the typo by just running the wsgi script from the command line. For example:

cd /usr/local/www/wsgi-scripts/ python djangolauncher.wsgi

I just faced the same problem so I started looking around.

Now I've got it working, so I thought I should share it with you guys!

All I did was do chown user:group /to/path -R and chmod 770 /to/path -R all over again and it worked.

chown user:group /to/path -R

chmod 770 /to/path -R

Setup: Ubuntu 14.04, Django 1.10, Python 3.5 (in virtualenv).

virtualenv

I tried many of these solutions without luck, but then I noticed that the Apache error log contains two different errors in my case. One that happens when someone tries to visit a page, another that happens at start up. I missed the startup one because I usually tried to refresh the page a couple of times and thus only saw the on visit error repeated a few times.

I then searched for solutions to the startup error instead and the solution to this question worked for me. Briefly, it involves updating the mod_wsgi package in a roundabout way.

mod_wsgi

I had been receiving warnings for months about the mismatch in mod_wsgi versions, but suddenly it resulted in Apache error 500's. Doesn't make any sense to me.

mod_wsgi

My guess is that this RuntimeError: populate() isn't reentrant error is usually a sign that one should look for a startup error, which indicates the real problem.

RuntimeError: populate() isn't reentrant

on visit

start up

[Sat Oct 15 03:38:08.900966 2016] [:error] [pid 28272] [remote 95.166.81.114:39651] mod_wsgi (pid=28272): Target WSGI script '/django/GP/GP/wsgi.py' cannot be loaded as Python module. [Sat Oct 15 03:38:08.901409 2016] [:error] [pid 28272] [remote 95.166.81.114:39651] mod_wsgi (pid=28272): Exception occurred processing WSGI script '/django/GP/GP/wsgi.py'. [Sat Oct 15 03:38:08.901662 2016] [:error] [pid 28272] [remote 95.166.81.114:39651] Traceback (most recent call last): [Sat Oct 15 03:38:08.902184 2016] [:error] [pid 28272] [remote 95.166.81.114:39651] File "/django/GP/GP/wsgi.py", line 16, in <module> [Sat Oct 15 03:38:08.902217 2016] [:error] [pid 28272] [remote 95.166.81.114:39651] application = get_wsgi_application() [Sat Oct 15 03:38:08.902501 2016] [:error] [pid 28272] [remote 95.166.81.114:39651] File "/django/env/lib/python3.5/site-packages/django/core/wsgi.py", line 13, in get_wsgi_application [Sat Oct 15 03:38:08.902529 2016] [:error] [pid 28272] [remote 95.166.81.114:39651] django.setup(set_prefix=False) [Sat Oct 15 03:38:08.902726 2016] [:error] [pid 28272] [remote 95.166.81.114:39651] File "/django/env/lib/python3.5/site-packages/django/__init__.py", line 27, in setup [Sat Oct 15 03:38:08.902755 2016] [:error] [pid 28272] [remote 95.166.81.114:39651] apps.populate(settings.INSTALLED_APPS) [Sat Oct 15 03:38:08.902924 2016] [:error] [pid 28272] [remote 95.166.81.114:39651] File "/django/env/lib/python3.5/site-packages/django/apps/registry.py", line 78, in populate [Sat Oct 15 03:38:08.902953 2016] [:error] [pid 28272] [remote 95.166.81.114:39651] raise RuntimeError("populate() isn't reentrant") [Sat Oct 15 03:38:08.903111 2016] [:error] [pid 28272] [remote 95.166.81.114:39651] RuntimeError: populate() isn't reentrant [Sat Oct 15 03:38:43.291502 2016] [:error] [pid 28272] Exception ignored in: <module 'threading' from '/usr/lib/python3.4/threading.py'> [Sat Oct 15 03:38:43.291579 2016] [:error] [pid 28272] Traceback (most recent call last): [Sat Oct 15 03:38:43.291604 2016] [:error] [pid 28272] File "/usr/lib/python3.4/threading.py", line 1288, in _shutdown [Sat Oct 15 03:38:43.292356 2016] [:error] [pid 28272] assert tlock is not None [Sat Oct 15 03:38:43.292377 2016] [:error] [pid 28272] AssertionError: [Fri Oct 14 23:38:43.412942 2016] [:error] [pid 28299] Exception ignored in: <module 'threading' from '/usr/lib/python3.4/threading.py'> [Fri Oct 14 23:38:43.413044 2016] [:error] [pid 28299] Traceback (most recent call last): [Fri Oct 14 23:38:43.413076 2016] [:error] [pid 28299] File "/usr/lib/python3.4/threading.py", line 1288, in _shutdown [Fri Oct 14 23:38:43.425037 2016] [:error] [pid 28275] Exception ignored in: <module 'threading' from '/usr/lib/python3.4/threading.py'> [Fri Oct 14 23:38:43.425125 2016] [:error] [pid 28275] Traceback (most recent call last): [Fri Oct 14 23:38:43.425157 2016] [:error] [pid 28275] File "/usr/lib/python3.4/threading.py", line 1288, in _shutdown [Fri Oct 14 23:38:43.427625 2016] [:error] [pid 28274] Exception ignored in: <module 'threading' from '/usr/lib/python3.4/threading.py'> [Fri Oct 14 23:38:43.427694 2016] [:error] [pid 28274] Traceback (most recent call last): [Fri Oct 14 23:38:43.427722 2016] [:error] [pid 28274] File "/usr/lib/python3.4/threading.py", line 1288, in _shutdown [Fri Oct 14 23:38:43.432020 2016] [:error] [pid 28273] Exception ignored in: <module 'threading' from '/usr/lib/python3.4/threading.py'> [Fri Oct 14 23:38:43.432078 2016] [:error] [pid 28273] Traceback (most recent call last): [Fri Oct 14 23:38:43.432105 2016] [:error] [pid 28273] File "/usr/lib/python3.4/threading.py", line 1288, in _shutdown [Fri Oct 14 23:38:43.438577 2016] [:error] [pid 28299] assert tlock is not None [Fri Oct 14 23:38:43.438654 2016] [:error] [pid 28299] AssertionError: [Fri Oct 14 23:38:43.442174 2016] [:error] [pid 28274] assert tlock is not None [Fri Oct 14 23:38:43.442226 2016] [:error] [pid 28274] AssertionError: [Fri Oct 14 23:38:43.447227 2016] [:error] [pid 28276] Exception ignored in: <module 'threading' from '/usr/lib/python3.4/threading.py'> [Fri Oct 14 23:38:43.447294 2016] [:error] [pid 28276] Traceback (most recent call last): [Fri Oct 14 23:38:43.447326 2016] [:error] [pid 28276] File "/usr/lib/python3.4/threading.py", line 1288, in _shutdown [Fri Oct 14 23:38:43.448813 2016] [:error] [pid 28277] Exception ignored in: <module 'threading' from '/usr/lib/python3.4/threading.py'> [Fri Oct 14 23:38:43.448876 2016] [:error] [pid 28277] Traceback (most recent call last): [Fri Oct 14 23:38:43.448903 2016] [:error] [pid 28277] File "/usr/lib/python3.4/threading.py", line 1288, in _shutdown [Fri Oct 14 23:38:43.450188 2016] [:error] [pid 28273] assert tlock is not None [Fri Oct 14 23:38:43.450231 2016] [:error] [pid 28273] AssertionError: [Fri Oct 14 23:38:43.456680 2016] [:error] [pid 28275] assert tlock is not None [Fri Oct 14 23:38:43.456737 2016] [:error] [pid 28275] AssertionError: [Fri Oct 14 23:38:43.461761 2016] [:error] [pid 28277] assert tlock is not None [Fri Oct 14 23:38:43.461826 2016] [:error] [pid 28277] AssertionError: [Fri Oct 14 23:38:43.466165 2016] [:error] [pid 28276] assert tlock is not None [Fri Oct 14 23:38:43.466219 2016] [:error] [pid 28276] AssertionError: [Fri Oct 14 23:38:43.658971 2016] [mpm_prefork:notice] [pid 28268] AH00169: caught SIGTERM, shutting down [Sat Oct 15 03:38:43.691909 2016] [:error] [pid 28272] Exception ignored in: <module 'threading' from '/usr/lib/python3.4/threading.py'> [Sat Oct 15 03:38:43.691968 2016] [:error] [pid 28272] Traceback (most recent call last): [Sat Oct 15 03:38:43.691996 2016] [:error] [pid 28272] File "/usr/lib/python3.4/threading.py", line 1288, in _shutdown [Sat Oct 15 03:38:43.693126 2016] [:error] [pid 28272] assert tlock is not None [Sat Oct 15 03:38:43.693159 2016] [:error] [pid 28272] AssertionError: [Fri Oct 14 23:38:44.490316 2016] [:warn] [pid 28349] mod_wsgi: Compiled for Python/3.4.0. [Fri Oct 14 23:38:44.490407 2016] [:warn] [pid 28349] mod_wsgi: Runtime using Python/3.4.3. [Fri Oct 14 23:38:44.505672 2016] [mpm_prefork:notice] [pid 28349] AH00163: Apache/2.4.7 (Ubuntu) PHP/5.5.9-1ubuntu4.19 mod_wsgi/3.4 Python/3.4.3 configured -- resuming normal operations [Fri Oct 14 23:38:44.505764 2016] [core:notice] [pid 28349] AH00094: Command line: '/usr/sbin/apache2'

Create a new question. Don't ask question as answers.
– Graham Dumpleton
Oct 15 '16 at 23:08

I'm not asking a question. Posting a solution to the same problem that worked for me. Apache throws error 500 and the error in the log file is the same as the one in the question asked here. Please reread my answer. :)
– Deleet
Oct 15 '16 at 23:14

Then include the actual solution in your answer rather than link out to another question. The problem is though that that other post doesn't mention the populate() issue at all and to me looks like an entirely different problem, so I can't see how you think it was solving the same issue. So as far as anyone can tell, you had a different problem which you should have asked a separate question for at the outset rather than confusing the responses here for what looks like a different problem based on details in that other post..
– Graham Dumpleton
Oct 16 '16 at 0:48

populate()

It's unnecessary to repeat the steps here. The errors appear in the same log, just that OP here didn't include all of it. One error is shown when the page is accessed (that's the part in OP here), another when Apache starts (that's the part in the other thread).
– Deleet
Oct 16 '16 at 8:13

I had this problem and couldn't find any answer why until I backtracked my commits. Apparently I had added an accidental import, because of auto-completion, that screwed up the setup.

# found in models.py from msilib.schema import SelfReg

In apache error log:
RuntimeError("populate() isn't reentrant")

It worked fine in my windows dev environment but failed on the ubuntu/apache server.

I was going into this same error after having change the order of this setting :

MIDDLEWARE_CLASSES = ( 'django.contrib.sessions.middleware.SessionMiddleware', 'django.middleware.common.CommonMiddleware', 'django.middleware.csrf.CsrfViewMiddleware', 'django.contrib.auth.middleware.AuthenticationMiddleware', 'django.contrib.auth.middleware.SessionAuthenticationMiddleware', 'django.contrib.messages.middleware.MessageMiddleware', 'django.middleware.clickjacking.XFrameOptionsMiddleware', 'django.middleware.security.SecurityMiddleware', )

putting it back on the order here before and restarting apache fixed the issue.

This can also be caused by having a duplicate entry in INSTALLED_APPS

INSTALLED_APPS

In my case, I had a custom renderer class for Django Rest Framework, for some purpose I had to override the renderer class's method "get_context" (full disclosure : to make django toolbar give correct SQL query count)

custom renderer class

Django Rest Framework

django toolbar

I removed that class and redeployed. It Worked.

I know it has been a while since this question was asked, but I just ran into this issue due to a problem I haven't seen discussed here. I was getting the RuntimeError: populate() isn't reentrant error due to SELinux on CentOS 7. I had Django served out of a home directory, and I simply had to enable the SELinux boolean that allowed reading home directories, as the populate() error was due to a permissions issue. The solution for me was setsebool -P httpd_read_user_content 1. I hope this helps someone having this issue.

RuntimeError: populate() isn't reentrant

setsebool -P httpd_read_user_content 1

In my case the error occured because a required pip-package was missing.

So I did a pip install -r requirements.txt, restarted apache and things worked again.

pip install -r requirements.txt

In my case, I had a circular import, which cause an error that break the populate method.

I solved problem with adding __init__.py to my apps folder.

__init__.py

touch /mainprojectfolder/projectfolderwhichcontainswsgi.py/apps/__init__.py

Then it worked!

To throw in my 2 Euro cents:

I recreated a working setup in Docker. The new Docker setup failed with

populate isn't reentrant

which seems to be a generic error.
In my case, I overlooked that

pip install Django

installs the latest version (2.0), instead of the required version 1.11.
Changing this to

2.0

1.11

pip install Django==1.11

fixed my problem.

Removing the virtualenv directory, recreating the virtualenv, then reinstalling all the requirements fixed it for me.

I think this is a generic error when something is wrong with settings.py. Sometimes I can find the problem by trial and error by removing the installed apps one at a time. In some cases, its not related to the installed apps. But from my experience, in all cases its a problem within the settings.py file.

settings.py

The multitude of answers makes it clear; this is a generic error that can have multiple root causes, typically related to loading Apache/WSGI.

All of these answers on this page should function as a kind of checklist, and in that vein I want to add the root cause of my instance of this error: failure to add an 'import os' to your settings.py file.

Specifically, we had a developer on our team who intended to remove an unneeded package, and instead removed 'import os' from the top of the production settings.py file. After an apache restart, our application wouldn't restart and we received the dreaded 'RuntimeError: populate() isn't reentrant' error.

A quick 'python manage.py check' did not reveal the issue, but a 'python settings.py' did; the os package was not loaded.

If you have this error, focus your search on checking your settings.py file(s) and also your WSGI file.

More importantly, ensure you go back in the error log and look for the very first error message that occurs after a restart of one of the Apache or mod_wsgi daemon processes. That first error will tell you the true reason for the error, any requests after that for the same process will mention the reentrant error only. In daemon mode, also ensure you are using startup-timeout option if you have this problem due to transient errors, rather than coding errors. At least that way it can automatically recover.
– Graham Dumpleton
Apr 9 at 21:03

reentrant

startup-timeout

This error also generated if inconsistence use of space and tab in code.

check if you have mentioned your api names twice in the settings.py ' s installed app section.

Application definition

INSTALLED_APPS = [ ... 'rest_framework', 'myapp_api', 'myapp_api.apps.myappWebserviceApiConfig', ]

Application definition

INSTALLED_APPS = [ ... 'rest_framework', 'myapp_api.apps.myappWebserviceApiConfig', ]

Removing duplicate entries solved my problem

but the tutorial says INSTALLED_APPS = [ 'allauth', 'allauth.account', 'allauth.socialaccount',]
– ming
Jul 4 at 0:50

This couse of lack of memory on your PC/Host/VPS, free some memory and all will be fine.

You've posted the same answer to three questions. Please tailor each answer to the question.
– Undo♦
Sep 21 '15 at 16:26

Why the downvotes? This was the correct answer for me.
– Babken Vardanyan
Jun 19 at 5:49

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