Ever since the recent upgrade of Mac High Sierra I had a very strange issue where I was not able to copy/paste from any application on my mac. I did a couple of restarts which didn’t yield in the result I was hoping for. And as usual with the right keyword search I was able to find a solution to this problem. Running the following command did the trick for me.
$ sudo update_dyld_shared_cache
The command took quite some time to run, so be patient and it does spit out some errors which is also normal.
So what this command does is it forces the system to re-check all of the dyld-cache. Apparently a bug in high-sierra causes the necessary libabries that aid in the copy and pase to get disconnected which results in this behavior. Link to apple forums