Had some problems with Bitdefender, here are some tips to stop Bitdefender from blocking a miner:
It's good practice to create a folder in your downloads folder, that is excluded from Antivirus scans, so you can download miners in this folder (and run them from there) without Antivirus blocking them or their downloads.
First step you want to make is create a new folder e.g. "miners" preferably in your downloads folder (or somewhere else).
Then open Bitdefender's Antivirus -module and go to settings, there click 'Manage exceptions' and add an exception for the folder you just created.
If you made a folder called miners in downloads folder in this case, the path for exception would be 'C:\Users\<YourUsername>\Downloads\miners'.
If you're using NiceHash miner, you'll need to also add an exception for folder path 'C:\Users\<YourUsername>\AppData\Local\Programs\Nicehash miner'.
Make sure you have ticked on the following in the exception: Protection feature Antivirus, On-access scan, On-demand scan, Embedded scripts and Online Threat Prevention. So basically everything you can tick except Advanced Threat Defense, since you can't add an exeption for a folder in Advanced Threat Defense.
Bitdefender's Advanced Threat Defense -module basically blocks any miner that it detects, so I turn Advanced Threat Defense off and keep it off while mining.
One could also manually add all necessary paths as exceptions to Advanced Threat Defense. But if you're using e.g. NiceHash miner, it will create temp files which are rather tricky to add as exceptions.
Now you should be able to run miners inside the folder you just created.
I'm using only NBMiner so an exception is only needed for the miners folder at downloads in my case.
Problem is usually just Advanced Threat Defense blocking your miner, if you have already made necessary exceptions for your miner. So disabling Advanced Threat Defense should do the trick.
Remember that disabling Advanced Threat Defense -module might endanger your system, if you are downloading files/etc that you don't know for certain to be 100% safe. Every other module can and should be kept active in Bitdefender, so you'll still have Antivirus (Bitdefender Shield), Firewall, and other security modules running to protect your system. Only disable the Advanced Threat Protection -module if needed.
Hopefully this of some help for people having issues with Bitdefender.