Step 1: On your already jailbroken device, launch the Cydia app from the Home screen and then switch to the Sources tab from the bottom.
Step 2: Hit Edit, then Add and enter the following repository: https://coolstar.org/publicrepo
Step 3: Search for and install the “Stashing for iOS 9.2 – 9.3.3” tweak as shown in the screenshot below.
This tweak/patch basically takes over the handling of where tweaks are installed on the device in order to get around existing issues with the size of certain data areas on iPhones/iPads with specific storage capacities.
With this “Stashing for iOS 9.2-9.3.3” tweak installed, Cydia will install tweaks on the iPhone’s or iPad’s data partition, saving valuable space in the process. Magic!
This should hopefully get you up and running nice and quickly, so be sure to enjoy your jailbreak!
Alternate method:
If the above method doesn’t fix your problem, try the following:
Step 1. Install Apple File Conduit “2” on the device from Cydia.
Step 2. Next, install iFunbox on your computer and then connect your iOS to your computer.
Step 3: Launch iFunbox. From the left column where your connected device is shown, click on Raw File System.
Step 4: Now on the right column where files and folders are shown, find and rename the file/.cydia_no_stash to /.cydia_no_stash-
Step 5: Once done, disconnect your device from computer and open Cydia, it should start preparing file system this time.
You can do the above with iFile too instead of iFunbox if you have iFile installed on the device.
ALL CREDIT GOES TO: Oliver Haslam
@
http://www.redmondpie.com/fix-failed-in-buffer_writefd-8-ret-1-cydia-error-after-ios-9.3.3-jailbreak-heres-how/