Modpacks won't load

[Rykierful]

I was prompted to download version 1.2.8 of the launcher, and now it won't load any of the modpacks. The logs give the error:
From Console: [Fatal Error] :7:3: The markup in the document following the root element must be well-formed.
Exception reading modpack file: org.xml.sax.SAXParseException; lineNumber: 7; columnNumber: 3; The markup in the document following the root element must be well-formed.

I've tried reinstalling the launcher, restarting, etc.

 

[AdamRobero]

I've had a problem with the new update aswell. Modpacks will load but I get told that it can't find the main class.

 

[Rykierful]

Aaaand I just fixed it. I guess when I updated java previously, it didn't completely install or something. Reinstalled it and it works!

 

[Coaster3000]

I found one way to fix it and that is to go to appdata and delete ftblauncher folder for a reinstall.

This actually fixed my problem.

 

[coats3789]

I was able to install the Horizons mod pack but it will not open. I have Pastebined the log http://pastebin.com/yNXhzVCs (debug mode) I am pretty sure there is a simple fix but I do not know what it is.

 

[Tikaran]

same as above http://pastebin.com/pvJ8i5Ae

 

[P46EY]

Getting the following after the updates stopped... http://pastebin.com/vXx4ynj0
So far Ive tried...
Reinstalling Java (reboot) same.
Deleting the ftb launcher and redownloading... Same problem
Deleting launcher, app data/ftb folder and redownloading.. Same problem



Console Debug mode pastbin http://pastebin.com/tp5Zfac6

 

[NEXUS2345]

I was able to install the Horizons mod pack but it will not open. I have Pastebined the log http://pastebin.com/yNXhzVCs (debug mode) I am pretty sure there is a simple fix but I do not know what it is.

Your problem is that the modpack is still downloading, patience is a virtue, give it a few more minutes.

I've had a problem with the new update aswell. Modpacks will load but I get told that it can't find the main class.

Your fix is to remove any spaces in the folder name where the modpacks and launcher are installed. So lets say you have a folder called 'Mod Packs', rename this to 'ModPacks' and it should be fixed

 

[idw929]

my problem is that it downloaded but it won't run horizon here's the report
http://pastebin.com/Bdnz556k

 

[Gaz_]

We are aware of the issues regarding the recent update to our launcher and the issues regarding the new modpacks. We are working on getting them fixed asap. Please keep an eye out on our twitter @FTB_Team or the forums for any updates.

Fixes that you can try:

Force Updating the modpack and wait 2-5min before closing the launcher after the download has finished