Brigadier

Change your selection under Account Settings > Signature > View Signatures? and you, too, will be able to see the info people post there. Just saying that it's configurable.

You didn't follow @goldenpsp's advice. Post a link to a log file for a game session that exhibits the problem (i.e. immediately quit the game and save the log file to a file sharing service such as Dropbox or similar). Which KSP and mod versions do you have installed? Please read this post about how you can support your problem report (the same link as the one in my sig block) and find the log file requested. It's difficult to help without some information on your install and game performance. If you're as new to the game as you are to the forums, you'll find that mod interactions can be tricky to diagnose and having the actual game data is often crucial to understanding what has happened.

Well, that's not entirely true and an unfair comment. CKAN MM installation works in the vast majority of normal cases but things can go wrong with outdated mods, reinstalls, accidental deletions, etc.

I'm sure it's working for you, and most mods can probably handle the update to KSP 1.9. It's good to know for reaction_wheel since he/she has some evidence that playing with FF installed is possible. There may be interactions with other mods that are causing this problem.

See the link in my sig block below for some guidance on problem reporting. Posting a link to your log file would be worth a try so we can see what might be going on. FF is not currently listed as compatible with 1.9+.

Sorry you're having so much trouble getting a working game. How are you installing your mods, via CKAN or manually? You still have lots of errors in the log file (370 to be precise, but not all of them are critical). I'm no log expert and you have a lot of mods installed. Are they all up-to-date and compatible with KSP 1.8.1? For example, PhotoSailer is generating errors related to incorrect texture format but you don't have the latest version, at least according to CKAN. Not that it's incompatible with 1.8.1, just a new version that might help reduce the error count. You seem to have multiple versions of ModuleManager.dll present. You should clean them out except for the latest version (4.1.3) since, according to the log, MM v3.1.3 is being selected for use. Probably not a critical issue, though. I would suggest creating a separate, clean KSP 1.8.1 install. Run it. Then install RB and see if you can replicate the problem. If you can't, continue to add mods in groups of 5-10 until the error repeats or you get all of your mods installed. Those wiser than I am might find the root cause faster but I don't see a major issue with RB other than an problemwith Urlum (which is in OPM).

The first apparent problem is with MiniAVC. It's creating a ton of log spam, which explains the size. And the log doesn't seem complete, either. There is a problem with MiniAVC, so consider disabling it with the mod ZeroMiniAVC. See this post

The best approach is to upload a file to a file sharing service, such as DropBox, GoogleDrive, or OneDrive, etc. and share it via a link in the post.

See the link in my sig block for description of where you can find the log files and more information about how to report a problem. KSP always produces logs. It sounds like an installation or version mismatch problem.

I raised an issue with the CKAN folks (https://github.com/KSP-CKAN/NetKAN/issues/7772) to limit TST v7.10 to KSP v1.9.x. I trust you don't mind, @JPLRepo?

If you mean does it break a save when adding it to an existing save, I don't believe so (but I have no first hand experience with 1.9), but ribbons will not be added retroactively (it can't go through your save to determine if any ribbon criteria have been met because most of that info is just not saved anywhere). You would have to add them manually. FF is really meant to be use from the start of a career save. I would seriously consider making a backup of your 1.9 save, install FF and see for yourself...just to be sure

I believe the config file there modifies certain orbital engines to use liquid fuel & oxidizer.

First, welcome to the forums. I hope we can get you an answer. Second, I would recommend not posting log extracts. They can be extremely annoying to those reading the forums on small devices and might not tell the whole story (clearly there's no error in what you've posted). Third, see the link in my sig block below for information on problem reporting and posting a link to your full log uploaded to a file sharing site. It'll help those trying to assist you when they can see more information, such as KSP and mod version, list of all mods you've installed, other errors, etc. You'll often see a comment from modders, "No log...no support". Sarbian is one of them

Read the post at the link below in my sig block for more information on what to post. At least post the versions of KSP and this mod you're using, a link to your player.log fine (if KSP 1.8+) uploaded to a file sharing service.

Just curious, what's the base of that log function? It makes a difference if I'm going to be the first person to ask?