Fast Raw viewer hangs


Fast raw viewer 1.3.3 Release bild 948(X64-directX9)
RAW files viewed: ARW, DNG, RW2
Windows 7 Service pack 1, Intel Core i/-2600K
When viewing files program hangs after some minuttes, not able to kill it via. Task Manager (process / applications), need to reboot windows and sometimes force shutdown (hold power button 5 secs). Hangs more after update to newest version.  Program is using approx. 1 GB. memory when it hangs.  Not running any other viewing software at time of hang. 
Using registred version

Dear Sir:

Where are the raw files located, please? External drive, card reader, network, local drive? How many raw files are there in the folder?

They are located on internal drives, both SSD and ordinary HD. There are from 30 to 1000 files in the folders.

Dear Sir:

Could you please run disk diagnostics?

I can try that tomorrow but it is only fast raw which have these issues and program hangs when accessing files on physical different harddrives. While lightroom does not have these error when accesing the files.

Dear Sir:

Would be good to run the disk check, to be sure. Do you have any other, non-raw files in those folders? Is the freeze repeatable? Have you noticed any specific actions that result in the freeze?

Not recognized any specific actions, and hang after varied usage time and on folders with different file formats. However all folders only have one specific image format in them, ie dng and rw2 not mixed in folders. However, some folders have movie files in them.

Dear Sir:

 What type of movie files? Does it freeze with folders not containing movie files?

Dear Sir:

'unable to kill' a frozen program via Task Manager means that the program halted somewhere within the hardware drivers.

There are two suspects:

 - graphics hardware

- or hdd/ssd subsystem.

If your hdd/ssd is OK, there is a very small chance that the problem is related to the storage subsystem, so the most probable place where it's freezing is the graphics hardware/drivers.

Is it correct, and are you using an on-CPU (i7-2600) GPU? If so, please make sure that you have the latest graphics drivers installed (here is the link to latest drivers: )

If your graphics hardware is not on-CPU but an external graphics card (NVidia/AMD), please make sure that you are using the latest drivers.

If the driver update does not help, try switching the FRV graphics engine to OpenGL. To do so, go to Preferences - GPU Processing - Graphics engine and restart FRV, or use the method described in in Manually Changing Graphics Modes section

If the graphics driver update/mode change does not help, we need a detailed 'program dump' for analysis. To create it:

 - wait until the next time FRV freezes

 - Open Task Manager

 - Find FastRawViewer.exe in the process list

 - Right click on it

 - select 'Create Dump file' from menu.

FastRawViewer.DMP will be created in your TEMP folder. Share it with us ( using a Dropbox / Google drive or any free file transfer service (WeTransfer, for example).


Sorry for late update, I have updated the GFX drivers and after using it a while more I have found out that it hangs when using my 4K monitor. Thats on duel display:
 - 1920 *1080 do not hang,
 - 3840 *2160 hang often, with images from different physical harddrives, do not hang with OpenGL
So I will try to continue to use it with OpenGl and report back if crashing continues. 
Thanks for good and informative answers, I have been away therefore I have responded late. 

Thank you for letting us know.

Our 'buggy graphics driver knowledge base' has +1 record :(


according to Intel:

Maximum supported resolution for HD3000 video (built-in into your CPU) is 2560x1600.

hmm what does that actually mean, I have a GFX card which supports 4K (NVIDIA GeForce GTX 970), and the resolution is 4K (i.e. monitor is at native resolution).  And only raw viewer hangs, DOTA 2, Lightroom, Photoshop etc all run fine.  But I have might have forgotten to mention I have a dedicated GFX card :(. My GeForce driver is 372.70 and I am running it on a stationary PC. 

Sorry, you do not mention GTX970 anywhere in above messages, so we assumed that you use processor GPU. We'll change our 'buggy database' to GTX970.

What exact driver version do you use?

BTW, I switched to Windows 8.1 just before monitor update to 4k and I use GTX970 too. This combo (Win8.1, GTX970, FRV) works fine in both OpenGL and DirectX modes.


According to Device manager
According to Nvida GeForce Experience 372.20, relese date 30.8.2016



I just built a system: 7700k@4.8ghz, ssd, gfx1060@4k. 4/5 times FastRawViewer hangs for ~40 seconds when opening. I've been testing with startup at a couple different folders. It does this even in a folder with only a couple jpgs, with DirectX and OpenGL. I tried to get a dmp file, but it was nearly 1gb.

Dear Sir:

(sorry for the long answer :)

Slow startup may be caused by 'problematic' disk drive (FRV queries all drive letters present in system for properties, than monitors all removable drives for media change), or by some broken drivers for other hardware (for example, one of our users has problems with Wacom Bamboo driver: if tablet was not connected to computer, driver initialization takes a long time; solved by driver update).

'Broken drive' may be, for example, drive letter connected to network storage, but NAS is not turned on, in this case drive query for properties will take a long time.

1. For disk drives query/monitoring problem we have this solution (mostly diagnostic, although you may work without Folders panel):

 - Close FRV

 - Navigate to "C:\Program Files\LibRaw\FastRawViewer\scripts" using Windows Explorer

 - double click on DisableFoldersOnStart.reg script, confirm you're want to run Registry Editor/Enter changes into Registry.

 - start FRV again

This script will disable opening Folders panel on program start and all logic behind this panel (disk drives/letters properties query, media monitoring, etc). This Folders panel still may be opened by F7 key (and will start all logic when opened).

If disabling Folders panel will help, the problem is definitely with drives query/monitoring logic (see section 3 below what may be done with it).

2. If it will not help, the problem is with other points. It may be not FRV itself, but some software (antivirus, etc) which monitors process memory (FRV allocates large memory chunks, so this monitoring may be slow). It also may be memory debugging settings if you're a software developer and use 'Debug Heap' settings (of MS Visual studio) in global environment settings (in this case MSVC runtime performs deep allocated memory analysis whitch is slow if large memory chunks are allocated.

To check against 3rd-party memory monitoring, please open Windows Task Manager window (Ctrl-Shift-Esc, select 'More details' in window bottom to show in details), than start FRV and see if any other process (antivirus, etc) will show big CPU usage.

If no suspicious activity is visible in Task Manager during FRV startup, we definitely will need dump file created during this delayed start. Without dump file we're unable to know what part of the FRV produces such delay.

To reduce Dump file size please

 - change Preferences - File Handling - Start without filename  to 'Empty screen', this will prevent recalling old folder

 - in Preferences - Performance please make sure you have not increase cache sizes from defaults (12 for RAW and 20 for JPEGs).

With these settings, DMP file of just-started FRV should be about 300Mb, and will compress (by zip/7zip/rar) to 80-100Mb. Please send the DMP file to us using any file sharing service (, dropbox, google drive, MS One Drive, etc)

3. What to do if the problem is caused by disk drive

1st: enable standard folders behaviour back:

 - Close FRV

 - run  EnableFoldersOnStart.reg script

 - Open FRV

 - open Folders panel by F7

 - Close and open FRV again to see if Folders panel is in place.

Solution 1: if you know what drive letter causes the problem (it may be disconnected network drive letter, bad card reader, not connected A: floppy drive, etc), you may disable access to some drive letters/path prefixes by registry settings.

To do that, copy ResetDisabledFolders.reg script from FRV scripts folder to some place where it is editable, and change "DisableFolderPaths"="" line to something like


(note the slashes, there are not Windows, but 'unix' slashes). Use drive letters of suspected drives instead of z: and q: in my sample.Than run this script. My sample will completely disables any access to z: and q: drive letters by FRV.

Solution 2: Simplified folders panel w/o any advanced features (context menus, media monitoring, etc):

Just run SimpleFoldersHandling.reg script while FRV is closed (NormalFoldersHandling.reg to revert it back).

Hope, your problem is with disk drives/network storage, not with other software/drivers. In this cases diagnostic (part 1) and one of solutions above will definitely help. If not, please send us DMP file created during slow FRV start.


Sorry, Windows 10.

The problem seems to have disappeared for now, but I suspect it was a drive. I did switch card readers at some point. It might have stopped then. Thanks!

Broken card reader with damaged controller (e.g. controller thinks card is present, while it is not) may result in long timeouts if drive letter queried by system/program.

It is better to un-assign drive letters for unused slots or/and use DisableFolderPaths tunable described above to disable access to unused slots.

Meanwhile, great to hear that the problem gone.

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