Question Install Error

That seems to be the case. It worked on 1.5.6 without a problem. 1.5.9 it does not.

FTP option is not enabled on the backend.
Kunera directory does not exist in either location.

There must be something different between those two environments. 1.5.9 has no differences in regards to the installer and we use it all the time to test our latest builds. This site is also running 1.5.9

I'm sure there is.. components, permissions, etc. It's not an exact duplicate. I just am at a loss of how to proceed considering I can't get the installer to tell me anything other than...

Install Error

No other info. No obvious permission problems. Nothing in the logs. And other components can be installed.

Have you tried another legacy 1.0.x component?

What file type are you suing when you try the install? I assume it is the .zip version of our built. Can you confirm?
Not all compression options will work on all systems. It depends what tools are installed on the webserver.

Docman is still 1.0 legacy and uploaded fine. While I don't have many, there are 2 other components that are not 1.5 native.

Fireboard being one of them.
Some stuff from AEC.
JoomlaXplorer
JVLinx

I've always tried the .zip component. It's what I've used for all my component uploads.

Using ThirdSphere as my web host.

Before commenting on this install error I installed Kunena 1.0.7b into a new Joomla installation 1.59. I used a new template also with a quick start package from a template club. Kunena installed without any issues with the exception of some minor template issues that have been around for a while, stick to default_ex and it's fairly good.

I am wondering if it isn't AEC that is causing your install error since it hacks Community Builder files and some CB files must be in Kunena for the two to hook up if wanted. Can't comment on the other components you listed but I have used AEC. Did you try un-hacking the AEC files first? Just an idea.

Legacy plugin -yes
PHP 5+ - yes
MySQL 5+ - yes
Joomla 1.59
Fresh install no old Fireboard installation