An error occurred installing iOS 9 Public Beta 1

It's very likely because of how overloaded the servers are at the moment. There are reports of people with that error message you got having to try 3 or more times before it worked. So either leave it for a while or keep trying 🙂

I just kept hitting install and it eventually worked

Save here. Five times and it worked.

Yes, Same error for me also. As said, tried 3-4 times but no luck.

I've now tried it more than 20 times, still no luck :( Still getting the error message: Unable to install update An error occured installing iOS 9 Public Beta 1

I restarted my iPhone and it worked

Tried 10 times, didn't work.

Restarted my iPhone, didn't work.

Tried again 3-4 times, and it worked.

It's all about hard working.

Yup, just keep trying. After restarting the phone it worked for me.

Hey

It worked for me.Just don't let the screen go off. Please hold the finger on it until it completes the download.

It worked for me.Just don't let the screen go off. Please move the finger on it until it completes the download.

I tried 4 times on my iphone 6 plus and it finally worked. iPad mini 2 however I have attempted 6 times and still no luck. Will continue to try

You just have to keep trying. I tried unaccountable times but when i killed all task include the setting and reopen it again and install it worked. Just keep trying

Closed all running apps and it seems to be working now.

Thanks for the tip sattar! It solved the lroblem! I hope iOS 9 and ElCaptain become much more stable, because since iOS 7 and mainly Yosemite, it's frequent to experience some freezing or crash in Apple softwares. I've just abandoned Windows many years ago because its instability... Let's see if Apple will improve their software.

Beta 1? The current version is beta 3. Betas do expire and your phone won't work until you update to a newer version. You should update to the newest one soon.