Missing write permissions in directory pub/static when run bin/magento setup:upgrade

TL;DR truncate pub/static folder.

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For me, I had an older installation, which probably had some symlinks and old files which no longer exist.

The issue checkInstallationFilePermissions is that it checks the permissions recursively. Files and folders. I had a missing symlink, and that returned false on the check if it's writable.

How to debug:

1. setup/src/Magento/Setup/Model/FilePermissions.php

2. Goto line 143 in method checkRecursiveDirectories

3. Add the lines var_dump($subDirectory);var_dump($subDirectory->isWritable());

4. Re run bin/magento setup:upgrade

now you'll see what is really wrong, and you can fix it. Personally i remove everything in pub/static, this will be auto generated content so you should not be worried about that.

I ran into this error in development because of a broken symbolic link.

I had created a file in a module's view/frontend/web directory that in developer mode was deployed to the pub/static directory using a symbolic link that pointed to the module's directory where the original file is stored.

At some point in development I removed the file from my module, but the symbolic link still existed in pub/static pointing to a file that no longer existed. I expect this would also be the case if I had renamed one of the files.

If a site is in production mode and has had bin/magento setup:static-content:deploy run, that actually copies the files to the pub/static directory instead of creating symbolic links.

In order to find this broken symbolic link I ran a command from the shell

find -L . -type l

Removing the broken symbolic link resolved the problem (for example using find -L . -type l -exec rm {} \;).

Inside your Magento root directory run the commands below and your issue should be gone:

$ rm -rf pub/static/*
$ php bin/magento setup:static-content:deploy

Worked for me.