I had a partial download in the old downloader but since the release of the new downloader, the old downloader refuses to authenticate (the new downloader authenticates fine). Is there any way to re-use the partial download from the old downloader? I live in a land of limited download quotas and would prefer not to have to re-download 2GB that I've already got.

The MD5 system can be seen by peering into GOG Downloader's .crc files. Despite the name, these files track MD5 hashes, and not CRC hashes.

Here's the first line from Dragonsphere's MD5 file, setup_dragonsphere.exe.crc:
<file name="setup_dragonsphere.exe" available="1" notavailablemsg="" md5="3406746bdca0b37d467d8eb8409f5b92" chunks="8" timestamp="2011-04-21 14:23:24" total_size="83690477">

md5="3406746bdca0b37d467d8eb8409f5b92" - This perfectly matches against the MD5 of the working setup_dragonsphere.exe file if you care to check it yourself.

timestamp="2011-04-21 14:23:24" - I installed Dragonsphere today, and the date is 6th of May, 2011. It's likely that "2011-04-21 14:23:24" is when the MD5 hash file for this version of setup_dragonsphere.exe was generated by GOG.

chunks="8" The larger your setup_[gametitle].exe is, the more chunks you'll have. Each chunk is approx 10MB [10485760 bytes]. setup_dragonsphere.exe is 79MB and has 8 chunks. setup_teenagent.exe is 8MB and has 1 chunk. setup_settlers5.exe is 900MB and has 91 chunks.

Every setup_[gametitle].exe file is divided into chunks. Each of those chunks has a separate MD5 calculated and stored in the game's .crc file. So, setup_teenagent.exe with its 1 chunk has a very small .crc file, with only 2 MD5s listed. setup_settlers5.exe with its 91 chunks has a lengthy 92 MD5's stored [MD5's for each of the 91 chunks + 1 MD5 for the total file].

Here's an example of Dragonsphere's complete .crc file including the hashes for its 8 chunks.

<file name="setup_dragonsphere.exe" available="1" notavailablemsg="" md5="3406746bdca0b37d467d8eb8409f5b92" chunks="8" timestamp="2011-04-21 14:23:24" total_size="83690477">
<chunk id="0" from="0" to="10485759" method="md5">bd841faac9de8519f8c1df1a4e0f3b15</chunk>
<chunk id="1" from="10485760" to="20971519" method="md5">87018fbf2fc1fccc83ddb285e7220c35</chunk>
<chunk id="2" from="20971520" to="31457279" method="md5">bea08ae047612a7ce632b5c5d7463b0b</chunk>
<chunk id="3" from="31457280" to="41943039" method="md5">f6a2bba4c9a905d3a9b77dd1eeed1677</chunk>
<chunk id="4" from="41943040" to="52428799" method="md5">8847e25e82dc4b9d4ce9c814099fad11</chunk>
<chunk id="5" from="52428800" to="62914559" method="md5">70ed75a6fa1caa52eb58fd47a50aaf15</chunk>
<chunk id="6" from="62914560" to="73400319" method="md5">d44f93f51820f2532d57f46cab70cd20</chunk>
<chunk id="7" from="73400320" to="83690476" method="md5">bb54e892933b3ba7aa331ff67d376aed</chunk>
</file>

In theory, if part of your setup_[gametitle].exe file is broken, the GOGDownloader should be able to analyse the file, generate a bunch of hashes, and then only replace the chunk[s] that don't match with GOG's MD5 hashes.

I haven't been able to get this to work for me. To test this, I altered a header in setup_settlers5.exe [enough to change the hash, but not the size] and prompted GOG.com to take another look at the file [right click the game in the GOG Download client and select Launch Installer to make it check the file integrity]. Instead of repairing it, GOG.com gave me an error message and asked me to re-download the entire 900MB file.

"The setup files are corrupted. Please download a new copy of the program."

At least the MD5 file integrity check definitely works. That's a great improvement.

We still might be able to perform our own chunk-based error corrections, or prompt the GOG Downloader to do it for us, by using a program such as Splits to break the exe down into 10485760 byte chunks. It's an avenue worth exploring, anyway.

Other things to note about the .crc files:

If you delete the .crc file directory and then turn on GOG Downloader, the setup_[gametitle].exe file will be promptly deleted and the Downloader will begin re-downloading the file from GOG.com. So, don't do that.

You aren't alone. I've got a chessmaster_9000_part0.gogDownload file myself that I'd like to complete. It's part of the reason that I've been digging into the new downloader.

I haven't figured out a way to do it yet. There might be one, but I doubt it'll be easy.

The old temp file format was just: [gametitle]_part0.gogDownload and that was it until it completed.

The new temp file format is split into 10MB chunks. So a 901MB would be about 91 chunks. It'd probably look like this:

setup_[gametitle].exe.chunk0_downloading
setup_[gametitle].exe.chunk1_downloading
setup_[gametitle].exe.chunk2_downloading
...
setup_[gametitle].exe.chunk90_downloading

If there is a way to use our old partial downloads then it probably involves having split our temp file into the correct size chunks and hope that the GOG Downloader stitches them back together.

It's a bit of a long shot really. Hopefully there's a better way.

I can't even open the new downloader update. I click on it and I get an error when opening it via an extractor.

I tried opening my old downloader and it won't let me log in at all. I tried changing my pass word several times, but I still get the same error.

I deleted my old downloader and tried again to download the updated GOG downloader by saving the file to my desktop, but when I try to extract the file to my desktop, I keep getting this message from my unzipper:
[deleted]

I tried doing it again and got this message:

[deleted]

My windows 7 unzipper states the file is invalid as well.

Any help or advise welcome.


EDIT:
Okay, never mind, I figured out that the problem is the version I downloaded. The download link provided at the account page doesn't work at all, however, after downloading the latest update from the following link, I managed to get it all working just fine.
http://wwww.gog.com/en/forum/general/introducing_the_new_gog_downloader_wip

I have the EXACT same problem

win7 ultimate / 64 bit.

7zip, default windows zip program, etc can't unzip the file.

edit: apparently you CAN download using browser.. sorry :p

Jadelith, read my edited post and see if it works for you as well.
Good luck.

Are we still having trouble with this? Because I have a 1.4MB wireless connection currently and my file is still not downloading... Tips anyone?

I am unable to download the downloader. The file it supposed to be over 1 meg, I tried twice, each time eactly 519kb was downloaded and I am getting "Unexpected end of archive" error. Any ideas?

I am using the link I got at my games page: http://files.gog.com/downloader/gogdownloader_0901372.zip

Same problem for me (Opera, FF, IE9).

This also occurs for me.

Try this one: http://www.gog.com/download/GOGDownloader.0.9.0.1336.zip

Same thing happens on new link: you get a corrupted download message when you try to unzip it.
Looks as if GOG has done it again...........

That one worked, Thanks! I'm also getting the 509 KB error on the other one.