问题
After installing yii2, I got the following error.
Some suggests that I should give full permissions to IIS_IUSRS but still to no avail.
回答1:
You shouldn't need to set the permissions to 777, that is a security problem as it gives read and write access to the world.
It may be that your apache user does not have read/write permissions on the directory.
If you use Ubuntu do this :
Make sure all files are owned by the Apache group and user. In Ubuntu it is the www-data group and user
chown -R www-data:www-data /path/to/webserver/www
Next enabled all members of the www-data group to read and write files
chmod -R g+rw /path/to/webserver/www
The php mkdir() function should now work without returning errors
来源：https://stackoverflow.com/questions/41539915/mkdir-permission-denied-in-yii2