I’m not able to install the IOS version 15.5

without more information, no one could possibly tell you why.

have you read thru this support article for updating?

Update your iPhone, iPad, or iPod touch - Apple Support

need more storage for update?

If you need more space for an update on your iPhone, iPad, or iPod touch - Apple Support

issues?

Updating iOS: common issues and solutions - Apple Community

video..

oleg.b wrote:

Can you describe the issue you get? Probably you need to install the Profile, but this depends what error you get

you think the OP needs to install a profile to get the current public release of iOS?

if anything, reverting back from beta the OP would want to uninstall the profile

Op asked about installing iOS 15.5.. This is the currently released iOS version.

Op did not mention beta and the average user does not use beta.. so you only muddied the waters by bringing up profiles with no implication from the Op. You think they are coming to these forums to trying installing iOS 15.5 beta? What sense does that make? They would ask about iOS 15.6 or iOS 16.

If Op had asked about installing iOS 15.6, then sure, you could be right. But that is not what was asked. And this community is not the place for beta discussions anyways.

That is all I'm arguing here.. you stated that in order to install iOS 15.5 that the Op 'probably needs to install the profile'.. which is simply not true.

Ultimately we won't know anything until we hear back with more details.

What happens when you try? Tell us any error messages that are shown on your phone.

Can you describe the issue you get? Probably you need to install the Profile, but this depends what error you get

One again depends on the error. Still to install Public Beta, yes Profile is required.