Hi @Soha,
It's been a while since we've seen the dreaded 0x8 error. I notice you are running 2017.12 which had an early release with this issue.
Could you provide the results of qiime info? You may just need to update to the latest QIIME 2 (in fact I would recommend that in either case!)
Otherwise, do you have an RStudio installation alongside QIIME 2 (or any other installation of R)? The library paths are known to conflict with each other causing this issue as well. In that case use:
echo ".libPaths(.libPaths()[2])" > ~/.Rprofile
to correct the problem, although this will come at the cost of RStudio's packages.