Add hook_requirements() to ensure a valid temporary directory

I had a similar error after uploading my local site to my dev site (on Pantheon).

Warning: file_put_contents(temporary://filerpztfq): failed to open stream: "DrupalTemporaryStreamWrapper::stream_open" call failed in file_unmanaged_save_data() (line 1904 of /srv/bindings/31e75de31e214292a19eca3a06b11c03/code/includes/file.inc).
The file could not be created.

In addition my admin menu bar wouldn't show (css was shot) so I had a hard time trying to access admin pages.
I had to call the admin pages directly in the URL.

The culprit in my case turned out to be an incorrect temp directly. Once I changed it to /tmp (and cleared the cache) everything worked fine.

I would say this is a bug. There could be better error handling/messaging if there is an invalid temp directory.

as told on #1, I have done the things I listed below,

- create a tmp directory under the files directory
- configure file system (admin/config/media/file-system)
- flush all cache.

voila! now it's working properly. thank you @mototribe :)

I had the same errors; I think the problem was that with updating, I deleted the 'tmp' folder, that doesn't come with the update, and then Drupal doesn't find it and shows error. To avoid this in the future I put 'tmp' inside 'sites', please, correct me if Im wrong:
The soution for me is:
1.- Creating a 'tmp' folder inside 'sites' folder (until this moment this was in the root, out of 'sites' folder)
2.- In Drupal admin go to 'configuration > File system'. There, in the field "temporal folder" write this path: "sites/tmp" and save.
3.- Flush cache in 'configuration > Performance'

Hope it helps

I just surfed to ADMINISTRATION -> CONFIGURATION -> MEDIA -> FILE SYSTEM and resaved without changes. Then I cleared the cache, and everything was fine. No changes necessary.

CONFIRMING STEPS in #4
also installing a localhost version of a dev-site that came from a Pantheon server and needed to do exactly this for the errors to clear.

thanks

I am doing a new installation with the Martplug distribution on shared hosting site. It looks like it has an invalid temporary directory with whatever is used by default on new installations. How can I change if I can't login to admin site?

•Warning: file_put_contents(temporary://filekYaJa7) [function.file-put-contents]: failed to open stream: "DrupalTemporaryStreamWrapper::stream_open" call failed in file_unmanaged_save_data() (line 1904 of /var/www/vhosts/domain.com/httpdocs/includes/file.inc).
•The file could not be created.

Maybe you can create a folder named 'tmp' in the root directory, this is what your Drupal needs, If this is the same problem I had. Drupal can not find this folder anymore (due to any update or something) and shows this warning.

This will be useful if your 'tmp' folder is set there in your 'config' (this is so by default).

I think then is necessary to clean your Drupal cache for the error-warning to go away. I don't know how to do this without accessing 'admin'. Maybe it happens automatically after some time?? (I don't kow)
This may help too with cache cleaning with php: http://drupal.org/node/42055

Anyway, I think this warning should not stop your log in. I would try to achive to log in first. And then follow #4 steps, to avoid this in future core updates.

Cheers

I created tmp folders everywhere and deleted contents from cache table and still no luck. You can't login as the account is temporary when in middle of install process it seems and not sure of the password. I can start all over again, but think I will be in same spot again.

I have just updated to 7.18 (running on OpenShift https://openshift.redhat.com/app/ - not sure if it is important) and seen same warnings.

I have tracked the problem to this function:

http://api.drupal.org/api/drupal/includes!file.inc/function/file_unmanaged_save_data

I do not know if file_put_contents can handle file path as an URI which is what drupal_tempnam('temporary://', 'file') returns here. So I made this hack in mine install:

-  $temp_name = drupal_tempnam('temporary://', 'file');
+  //$temp_name = drupal_tempnam('temporary://', 'file');
+  $temp_name = drupal_tempnam('/tmp/', 'file');

You should check the file system configuration to make sure it's actually pointing to /tmp rather than hard-coding.

Sounds like this could use a hook_requirements() addition to ensure that the temp directory configuration points to a valid one.