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Folding@Home FAHclient.exe access denied; FahCore_21.exe bug fix (Windows 10)

For those that don’t know folding at home is a distributed processing computer network which provides computing power for health research projects in the field of protein science, and is run by Stanford university.


Applications for this science range from cancer research, to alzheimers, and debilitating, terminal genetic diseases such as Motor Neurone Disease (MND) and even mad cow disease.

People all over the world for the last 15 years or so have donated their spare computing power, available on home computers, corporate servers and even gaming devices  in some cases.

These generous donations from the general public amount to an incredible amount of money in terms of hardware costs, internet bandwidth, and power consumption costs, plus time and effort of donors to configure and maintain their computers to run the folding at home software in a stable fashion, and make charitable contributions.

Folding at home currently supports both CPU and GPU (graphics card- AMD and NVIDIA) processing of scientific research.

Shortly after installing folding at home, and beginning to compete work units, I noticed a problem with the GPU- the required core file (the application that runs the GPU as a processing unit for folding at home) FahCore_21.exe and FahCore_a4.exe were having an issue shortly after downloading from the Stanford university website. : access is denied.

How to fix??

FahCore_21 access is denied failing

FIrstly, I looked at the firewall issues that could be stopping the FahClient program communicating with the outside world.

The following list of applications need to be enabled as authorized in the windows 10 firewall to ensure folding at home can run properly: fahclient.exe, FAHCoreWrapper.exe, FAHViewer.exe, FAHControl.exe, Core_21.exe

Its also a good idea to pin these apps to the start menu for easy access too- it doesnt happen by default when undertaking the standard install!

The core file may be different, depending on the age of your system and GPU / graphics card- (mine is an ancient dinosaur by comparison to modern gaming beast rigs) core i5 CPU + NVIDIA fermi GT 430 graphics GPU.

Fahclient folding@home windows firewall settings

Some of these folding at home client and core files can be a little tricky to find- their default direcotry locations are hidden in the rather hotchpotch file structure of windows 10 or windows 7

The main client and other key applications default file path is fairly easy to find on windows 10:

  • fahclient.exe default file path: C:\Program Files (x86)\FAHClient
    • This program controls the CPU calculations (folds proteins)
  • FAHCoreWrapper.exe default file path: C:\Program Files (x86)\FAHClient
    • This program allows GPU to be used for calculations too.
  • FAHViewer.exe default file path: C:\Program Files (x86)\FAHClient
    • This app visualises the protein folding itself you are undertaking, and renders a map showing the worldwide distribution of donors
  • FAHControl.exe default file path: C:\Program Files (x86)\FAHClient
    • Instead of using the web control to configure your client’s behaviur, login etc, (http://folding.stanford.edu/client/) you can use a local program instead.

The core files for the GPU processor are in a couple different possible locations:

Typically only under windows 7 – program data


on WINDOWS 10 – the appdata roaming folder under your user account


win 10 location of FahCore_21_exe for firewall allow

The last possible problem stopping the folding at home client from running properly is administrative privileges. Though your account might have administrative privileges, you may need to specify to use them when the F@H client is started- this can be set via the peoperties of the application file.

FahClient run as administrator settings

You will need to navigate to the file’s location in the file system and right click on it to change the default running preferences.

Check the box “run this program as administrator” and hit apply.

After all this is done, the access denied error on folding at home should be fixed.


Zcoin – Setting up the wallet to sync quickly with screenshots

The cryptocurrency craze is in full swing yet again, and zcoins are one of the key new currencies to emerge after the blistering succcess of bitcoin.

The status and mainstream use of digital coins has changed dramatically, and become a new asset class of late.

I’m curious, so have jumped on board to investigate what its all about.

Below is a graphic tutorial about how to set up your zcoin wallet quickly and easily, without having to wait forever for it to sync.

Downloading and syncing a bitcoin wallet, which is gigabytes in size seemed too arduous and time consuming for an impatient guy with only a cursory interest in the subject, so I chose Zcoin.


You can download the wallet program for your OS of choice at the address above.

The catch is that it seems to take aeons to sync the wallet, by downloading the blockchain and processing it.

Apparently the start up process for your wallet can take days to weeks, through the size of the blockchain itself is only quite small, at around 187Mb! (at time of writing)


zcoin_QT_wallet_sync_blockchain_slownessInternet speed seems to have precious little to do with it; its just mind numbingly SLOW!

A couple hours after installation, less than 7% of the estimated transactions int he chain have been downloaded and processed.


I thought I’d be clever, avoid the pain, and download the entire blockchain file in its entirety off Znode.


The whole download took just a few minutes at 1MB/Sec.Znode_zcoin_QT_wallet_sync_blockchain_very_fast_download

Next step is to extract the zip file, and put the files in their requisite places for the zcoin wallet to pick up.

The unzipping of the Zcoin block chain file from Znode is a very quick operation, taking less than a couple minutes.


As promised, the zip folder contained the “blocks” and “chainstate” folders, which need to be dumped into the USER\Appdata\Roaming\zcoin folder on windows operating systems


A bit of copy pasting later, and I have imported the downloaded full blockchain files into the zcoin wallet to give it a head start.

I took the cautious approach, and just changed the names of the current folders with their 7% progress with a BAK suffix, so I can restore and go back to doing the sync the long way if the process doesn’t work.


Just for interest, at present, the zcoin blocks folder is 243MB on disk, and the chainstate folder is a teeny 11MB. Of course, as time goes on, this will blow out to huge sizes, as the coin is in its relative infancy.

Now, to see how long the processing and sync takes once this little boost has been added…

Znode_zcoin_QT_wallet_sync_blockchain_imported_wallet_loadingAll looks healthy here… it just may take a little while.

Looking at the stats on the system performance, depicted below; the CPU is banging away at a modest 21% load from loading the wallet.

It may be hanging, but we will see what comes from this in a few hours.



The situation looks fairly positive though, as the wallet.DAT file is being constantly written to during this process.

Posts on the zcoin website indicate that the reason it takes so long is verification of no double spends.


I’ve taken note of the time the verification began, and will update this post once I have a definitive loading time.  A progress bar certainly would have been nice on the opening screen.

UPDATE! looks like it took about 5 hours to load the saved part of the blockchain…  only thing, its now 8 hours behind, so will take quite a while to sync up again. (More hours!!)

2017-06-30 14:40:12 init message: Loading wallet..
2017-06-30 20:07:49 PROCESS BLOCK = 41049

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