Why everytime i update unity i have to delete my Library folder?

Hi all so as of updating to unity 5 which was when it came out everytime i update to a new version the unity ui disappears and i have to delete my library folder to correct the issue , sometimes multiple times , sometimes i have to load a backup then reimport everything , which takes the whole day , and then that might not even work , my usual day of updating goes like this , download new version , start old project wait for re-import of assets (+-10 hours) then open unity discover i have no ui then delete library wait another (+-10 hours) still nothing so i delete everything except assets folder wait another (+-10 hours) , then sometimes it works sometimes i have rename my whole project again so unity will do its magic (voodoo stuff ) that usually does it sometimes not sometimes i have to make a new project then copy assets folder to new project, that usually is my last resort which normally works . what id like to know is where am i going wrong in updating my project ?

Some things that happen while upgrading usually unity pops up after updating with +999 warnings , unet stops working usually (unless i rename my project ) cant send anything (get spammed with errors no receiver for message xx), i also cant add ui components such as images and text directly from add component window as there is no ui to speak of , also most of the time when upgrading to new versions the asset importer just crashes , then i try again and it says something about a connection or something , then just keeps spamming i have to end it in task manager , so any tips or ideas on what i may be to doing wrong here would help and also an easier way to bring my ui back and unet back would be greatly appreciated .
Thanks for reading my semi rant !
also heres a screenshot of my inspector where the ui used to be its the same in all scenes in the project.

 

10 hours? Sounds like time to clean up your project. That is pretty excessive.
Updating isn't always smooth, some have things have changed by its very nature. The best bet is only update when you absolutely need it. If an update doesn't fix bug that you are actually experiencing, just skip it. (because there is always a chance that the update may introduce new bug).

 

agreed although i did need the update as there were alot of things that were bugged like particle systems so an update was neccessary , and coming from unity 5.1.3 i was lacking alot of features like multiscene editing unet fixes etc , but i agree im not updating for a while now as all the features i need are in this version, On another note i fixed it by deleting my assetdatabase file in my library , this seems to work the best , so for future users who have this problem delete your assetDatabase3 file in your library and wait till it reloads should slightly faster then a whole reload of the metadata .
Gonna clean my project up even though its only like 7 gb big its got alot of stuff in it , thanks @zombiegorilla for the tips!

 

Missing your UI generally means missing UI assemblies. When that happens, this tends to help.

Edit: This can also happen after certain types of editor crashes as well, so we always have a similar script on a menu item.

 

One thing that helps is having your images set to the target size and not use psds. That drastically cut down our import time. Still, 10hrs is a lot. Out of curiosity, are you using Resources folders, and if so, what do you have stored in them?

 

yes as a matter of fact i am using the resource folder , i used to have photon , and so i stored all prefabs in resource folders as well as a few textures not much , how would this impact load times ?
also after getting unity 5.3.1p3 to work i had none of the features of 5.3.1 such NetworkServer.SpawnWithClientAuthority and the new monodevelop wasnt in there still the old version (4.01) , im not sure whats going on i uninstalled it and installed unity 5.3.1f1 and all the normal features were there but in patch 3 they're all gone , and as far as i can tell this 5.3.1p3 is the same as unity 5.1 in its features infact they are identical

 

Also most of my project is textures , like theres alot of textures i should probably go delete the ones im not using .

 

It could be impacting your missing script problem. Guids are handled differently for things in resources. (Somewhat). It is not recommend by unity except for a few things and not for production games. Try moving and see it that helps. Though I don't think that is what is causing your long import times.

 

well no guis in there or textures on the gui , so doubt that thats it , yeah i think ill just run through and delete old textures and meshes im not using as most of it was for prototyping another game , any clue as to the other wierdness about unity 5.3.1p3 not having all the new features?

 

nevermind solved turns out somehow i ended up download unity 5.1.3p3 instead of unity 5.3.1p3 , not sure how