Unzipping modpack fails for some users.

[Ravenleft]

Launcher Version: Latest, possibly others

Operating System: Windows 7, possibly others

Java Version: Java 7 64 bit, possibly others

Antivirus Program: MS Essentials, possibly others

Description of Problem:

Description:

I'm running a private server with 4 players using a custom modpack via the technic platform.

When 2 of our users tries to update the modpack, the zip file is downloaded ok but is then only partly decompressed. No crashes, the MC client then usually launches without problems but the users can't connect to the server due to various mods missing.

Decompressing the file manually from the cache folder works and allows them to connect.

For the other 2 users this problem never occurs.

This problem started happening a few weeks/a month ago, before that no one had any problems.

This issue may be related to some of the reports in http://forums.technicpack.net/threads/error-uzipping-file.47203/ but at least the OP is not related as the errors he's getting points to something blocking the download leaving him with a 0 size zip which of course can't be unzipped (no valid zip header, MD5: Null, etc). In our case the zip always downloads and in the odd case where the download has failed in some manner it has been caused by connection issues.

Problem Troubleshooting:

Now, since it's working for 2 of us and not working for the other 2 I have tried to figure out what people have in common. What I've found is that the 2 of us who don't have this problem both have fairly new computers with quad core Core i7 CPUs, 8-16 GB RAM and SSD disks while the two who are having this problem both have more dated computers with Core 2 Duo CPUs, 4-6 GB RAM and mechanical disks.

Add that this problem didn't always occur but suddenly started happening a while ago. The only thing that has changed and that could reasonably have something to do with this (ie. I can't see how the Forge version could have anything to do with wether a zip is uncompressed successfully or not) is that the modpack.zip has grown in size.

Our modpack.zip has always been rather large and is now 77.7 MB in size, uncompressed it's 535 files, 85 folders and 179 MB. I'm not sure how large it was at first but I'm pretty sure it was around 60 MB at some point, no idea at all of how many files and folders it had.

Decompression always partly works, some files are unpacked properly while some files are left missing.

Possible Causes:

The problem may be related to how long it takes for the modpack.zip to unzip and that there is something, possibly in the launcher, that times out and cuts the decompression process short, regardless if it's done or not.

It could also be a caching problem, the unzip program often unzips files to a temp folder and then moves them to the final destination. It's possible this operation fails likely also because it's taking too long to finish and is then interrupted for some reason. (this is more of a wild guess, I have no further information that supports this at the moment.)

Final Thoughts:

I can't really say where I think the problem actually lies, is it something in the launcher that times out, is it the unzip program used that freaks out or is it something completely different?

The reason I posted this here is to share my information with the hope that there are others who can add more concrete information to help us all figure this out (I'm assuming this is at least loosely related to at least some of the others who have problems unpacking modpacks and that my case isn't unique).

Myself I'm going to do some hands on investigating (I have access to one of the computers involved) and if I find something new I'll add to this.

Error Messages:

None reported

Error Log:

Don't have one availible but I'll try to get logs from both of them and add them later if I find something interesting.