user cannot properly ask question how to fix it
But with all seriousness: you're giving way to less information for anyone to help you.
First, what are you talking about? Rockbox Utility? If so, which version? Also, what OS are you on? Also, what player are you trying to install Rockbox to? Where's the log file from Rockbox Utility?
Second, post in the correct forum. You have an issue with installing Rockbox with Rockbox Utility? Then it should go into the "Rockbox Utility" subforum. Its subtitle says "Questions relating to the use of Rockbox utility, including the installation of Rockbox using it.".
Last, please do your due diligence and search the forums first. At least look at the posts from the last couple of weeks. If you look into the Rockbox Utility subforum there are a couple of reports lately with installation errors. I'm suspecting you're hitting this
https://forums.rockbox.org/index.php/topic,54173.0.html or this
https://forums.rockbox.org/index.php/topic,54180.0.htmlBut without details from you this is just guessing.
Hint: People are usually much more willing to help if they don't have to guess what you're talking about.