alexandros050: It depends on the game...If the game is 30+GB of course it will take longer. GOG still uses the same method as before nothing has changed...Also it matters if you have an SSD.

NemesisSK: Hi folks,
having some very strange issues with the installer. Multiple games, it is not related to the games.
I remember that I never had issues with the older installers before. I do not use GOG Galaxy, just offline installers.
I am working constantly on identifying the issue, so will add information to this as I go.
Issue happens on my gaming rig, Win10 Enterprise 2016 LTSB v1607
Ryzen 7 1700 OCed thru P-states, ASUS ROG CROSSHAIR VI HERO

*Running game installation and getting multiple errors during install, maybe random, maybe not - YES RANDOM

Error during install: Internal error: Expression error 'Runtime Error (at 500:57): Out of string range.'
Error on installer finish: Runtime Error (at 210:63):Out Of Stack Range. + Runtime Error (at 210:69):Out Of Stack Range. + Out Of Stack Range.

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Solutions identified:
Seems that installing from local volume or network makes no difference.
Verification always passes, so data integrity is not the issue.
*Found that if I install this on my second machine (Win7 x64 Ultimate) the installer has no problems at all.
*Found that when this error happens, the files will not be completely unpacked, comparing it to a successful install on my W7 machine, the files were smaller, so issue is unpacking.

Seems DebugView is not getting any output to identify issues, nor is the Event log.

*Installation to HDD was successful, now testing installing to SSD on Win7 machine.
*Installation to SSD on Win7 successful. Issue must be related to OS or specific HW on W10 machine.
Installation again to W10 SSD. SSD TRIM was performed and setting affinity. - FAILED
--- no matter how many cores are used by affinity, tested 1-7
*Testing installation on Win7, but source is network on Win10 HDD, install destination is Win10 SSD network path-SUCCESS .. maybe NTFS stream handling that is not going thru network normally
*Testing installation on Win10, using normal drive as source, but using networked path as destination-FAILED
*Testing installing on the SSD system partition instead of data partition. - SUCCESS

Geez running out of ideas.. why would it be OK on C: but gives errors on D: if it is the same SSD drive

*Disk checks are all OK. Defragmented D: to have different blocks available - FAIL
*Compatibility mode to Win7 - FAIL
*Latest BIOS 6201 did not resolve the issue.

Found that sometimes it happens even when installing on C drive.. strange makes no sense..
Tested to format the drive with different cluster size or different file system.. no difference
***Started to shut down all non-critical services and programs running - WOOT.. now that sofar seems to be the solution
*Sofar, it seems that all is needed is to stop the Razer Chroma SDK service - testing more, happened again.. damn

Now why the hell would Razer Chroma SDK service have anything to do with GOG installer?
I remember that there was one game that would not start without that to be running as well.
But installer? And only GOG installer? Very strange...

Stopping the IDrive service as well.. sofar so good.. will test more installers as it is obviously intermitent
Strange behavior of some installers that would not start installing.. seems removing AMD Ryzen Master solved that..

OK all my testing is completed. Razer Chroma SDK was not the real issue. For some reason the real issue is the IDRIVE service, even thou it is not doing anything on D drive, as soon I stop the service, I do not have a problem installing. Must be some conflict between GOG installer and IDRIVE services.

Hope this helps the developers somehow in the future.

*****
Todo:
***Check if it always happens to the same files / if the files always have the same erroneous size. - NO, RANDOM
***Check if it is the SSD destination. - YES, this seems to be the case, installing to HDD has no issues.
***Check if it is CPU issue / threads / cores etc.. - Does not seem to be related to CPU core/threads
***Check if MB firmware can solve the SSD/OS compatibility issue. - NO, still same issue
***Identify what program / service is causing this. - IDrive service, with some impact of AMD Ryzen Master probably

kiaoking: Here is my simple solution: regardless which drive you are gonna install the game, leave enough space in your C drive (as much as the whole game needs).

After I had this issue and read read all the post above, I monitored the task manger-performance while installing a game to my D drive, but I found that my C drive was at 100% activation, and it was write at first, then about half through the installation it became read, and my D drive start to have a write mode. Another proof is my C drive freed up as much as the size of the game after the installation is done.

I suspect the installer will install the game to your C drive first then cut-paste to the drive you selected.

My guess may sound stupid but this should be easily confirmable by others.

Oh forgot to mention, I am on the latest WIN10, my C drive is a HDD and my D drive is SSD, game was downloaded to my D drive.

And the finished game folder name is over 30 letters long.