We recently updated an older site to Wordpress 5.3 and Divi theme 4.0.6, hosted on the Pantheon platform.
In doing so, we quickly found that we could no longer edit our pages as the Divi builder would not load. The error in the error logs was:
.../data/Utils.php:758 ET_Core_Data_Utils::WPFS():
[ERROR]: Unable to write to filesystem. Please ensure that the web server process has write access to the WordPress directory.
We realized that this was due to how Pantheon handles the wp-content filestore between environments and that we would need to create (and commit through Git) a symlink to the folder we needed:
https://pantheon.io/docs/assuming-write-access
For Divi theme, which was trying to write to three different (nested) folders in wp-content,
et-cache
global/
en-US/
This meant we needed to create a symlink in our wp-content folder to the uploads directory:
ln -s ./uploads/et-cache ./et-cache
And then login to each of our targeted Pantheon environments through SFTP and create these folders within the files directory, ex.
cd files
mkdir et-cache
cd et-cache
mkdir global
etc..
This seemed to work for some environments but wasn't consistent so we finally found a solution by digging into the Divi settings. The above errors are happening because Divi cannot load or save to the targeted directories to cache the results. We decided to forgo the cache to get the site back up and made that change here:
We had a similar issue with a Divi website on Pantheon. I had the same issue with a symlink et-cache folder not being a consistent fix and still getting problems once the filesystem was not writeable. One thing I didn't do was manually create the directory structure inside the et-cache folder, so maybe I'll give that a try again.