1. What Galaxy server are you working from? The main Galaxy instance is at http://usegalaxy.org and IGV is functioning as normal as far as I know.
2. What is the assigned reference genome (e.g. "database" attribute)? Is it supported by IGV?
3. Did you create the .vcf dataset in Galaxy or upload it? If uploaded, are you able to perform any other functions on it? Open it in Trackster ("Visualizations" within Galaxy)? Confirming the upload is important.
4. If you are trying to use a local IGV - open that application first, then click on the link.
Thanks - this additional investigation may help you solve the problem, or you can send back more info and we can try to help. You can also look at "Similar posts" at the left side of this window --> to see if any of the prior Q&A helps..
Best, Jen, Galaxy team