This is a documented issue with the launcher. To work around it: Download this file: http://www.java2s.com/Code/Jar/j/Downloadjoptsimple45jar.htm For your setup (Twitch) go to the folder: \Twitch\Minecraft\Install\libraries\net\sf\jopt-simple\jopt-simple\4.5 Replace the file in that folder with the one you downloaded earlier.
2. Click where the red box is in the image I've attached. 3. Remove any text in that box and type in what it says after Path in your image (C:\Users...) 4. There may be files in the location you end up in. Delete any files named "jopt-simple-4.6.jar". KEEP THIS WINDOW OPEN!! 5. Go to the link http://central.maven.org/maven2/net/sf/jopt-simple/jopt-simple/4.6/jopt-simple-4.6.jar ; it should just download the file you need. 6. Place the file it downloaded where you went to in step 4. 7. Run minecraft and feel free to tell me if any further issues occur.
I had a similar problem to jollymood, the error code path I got was in C:\Program Files (x86)\Minecraft Launcher\game\Install\libraries\net\sf\jopt-simple\jopt-simple\4.5 and i replaced the file there with the link provided by you in response to befitraptor82. When i tried running mc with my modpack, it crashed. I also know nothing about computers, can you help me..?
I was having the same problem, but instead of jopt-simple-4.6 jar it was 4.5 I deleted the jopt-simple-4.5 file and installed the 4.6 in the 7 steps above, but when I launched the Decimation modpack, the error popped up again, and when i went into files the jopt-simple-4.5 jar file was there even though I deleted it. I tried again, deleting the jopt-simple-4.5 jar file and relaunching the modpack, but it happened again. Even though I have the jopt-simple-4.6 jar file, it still just puts the jopt-simple-4.5 jar file back in.
I am having this issue where Minecraft will never fully download the modpack "Sky Factory 3" it will only download to 64.3 MB of the total 128 MB every time. I saw you had a solution to this exact issue with jollymood and so I followed your steps but Minecraft could still not launch the modpack. I repeated the process 4 times to no avail. Also, I'm not exactly sure why but I can use the modpack on a different account of this PC but just not my account. Could you please help me find what the issue might be.
Im having the EXACT same issue but when I type in what is says after path it is not taking me anywhere. I have tried everything to get it to take me somewhere but nothing so i can not add or delete files.
Please help ASAP as I have no computer skills and can not play any downloaded mods!