Thank you for the error message. This is a known problem.
The UTF-8 text encoding error was reported recently - but only by two people.
I have now prepared alternative coding to trap for this unexpected issue.
We still don't know exactly what's causing this UTF-8 encoding error, but it's now sidestepped to avoid these issues.
Also some very rare internet connectivity issues, which threw up unexplained errors, are now trapped with error messages if there is a download/unzip failure.
Version 5.0.2 is now ready and being tested in house, it should be published in a few days - watch for announcements.

To uninstall SketchUcation - close SketchUp.
Open your SketchUp's Plugins folder.
Find the file SketchUcation.rb and its subfolder SketchUcation.
Select them and delete them.
Open the PluginStore page and download the latest RBZ - currently it's v5.0.1 [but v5.0.2 will be released very soon].
Open SketchUp.
Use SketchUp's Extension Manager to install that RBZ.
If there's an error message copy it and paste it into a reply.
Otherwise, can you activate the SketchUcation extension if it's shown disabled ?

We have had a few reports of issues and many of these will be addressed in an update shortly.
However, we cannot be sure what your problem is without seeing the error messages.
On the dialog image which you posted there is a button in the bottom left-hand corner entitled
'Copia tutti gli errori' - 'Copy all errors'
If you click on that the error message is copied on to your Clipboard.
Then compose a post here, and Edit > Paste the Clipboard contents into it.

Abbiamo ricevuto alcune segnalazioni di problemi e molti di questi saranno risolti a breve in un aggiornamento.
Tuttavia, non possiamo essere certi di quale sia il tuo problema senza vedere i messaggi di errore.
Nell'immagine di dialogo che hai pubblicato, c'è un pulsante nell'angolo in basso a sinistra intitolato
'Copia tutti gli errori'.
Cliccandoci, il messaggio di errore viene copiato negli Appunti.
Quindi, scrivi un post qui e seleziona Modifica > Incolla il contenuto degli Appunti.

@alexpacio2013

Please use the 'Copia tutti...' button [bottom left] and copy/paste the error in a post

An updated SketchUcation RBZ is being tested and will be published shortly - this should avoid this error when one of Fredo's [or TT's] extensions is only partially uninstalled and the VERSION is therefore unavailable...

Thanks, the oddity of finding the VERSION of a @fredo6 extension like 'Fredo6_Curviloft', that is not loaded, i.e. it's shown as unloaded in our Plugins Manager because it's been renamed .RB! , is that we cannot get it by reading the extensions loading Fredo6_Curviloft.RB! file itself as Fredo doesn't expose it in that file [unlike most other authors]; instead we have to read the associated Fredo6_Curviloft.plugin file and find the VERSION there. If that file is not found we should skip to 'no version found status' - BUT somehow our checking is tripping up. I'll check and ensure there's a robust trap for this...
Please ensure that if you don't want it any more that you do not have any Fredo6_Curviloft files or subfolders in your Plugins folder - there must be something there to cause the error to arise...

At last !!
Thanks for the feedback. Sounds good to go ! I'll get something ready for Friday...
Are these FileUtils messages in anyway associated with SketchUcation stuff ?
Or is it something else entirely ??

@gullfo @tsur

The new version is attached to a PM for you.
We are very keen to earn of your results...

@gullfo @tsur

Thank you for your help and patience so far.
I've prepared an RBZ with new encoding code to hopefully sidestep the issue. I'll send you a copy by PM [chat], please install it and see if it helps. Let me know what's what...

@gullfo @tsur

I don't think it's the username - BUT clutching-at-straws...
The MAC system encoding is always UTF-8 as expected.
My PC is too.
@gullfo reported the same !

So now I need t look at why in just two cases reported to date there's an encoding error when none seem to be there...

Watch this space...

@gullfo @tsur
Can you open the Ruby Console and Copy/Paste this in +<enter>
It lists the RB files you have in your Plugins folder and their text encoding within them - all of mine return UTF-8 but yours might not ??

puts "\nFile Encodings...\n\n";
lp = Sketchup.find_support_file("Plugins");
rbs = Dir.entries(lp).find_all{|e| e=~/\.rb$/ };
rbsf=[];
rbs.each{|rb| rbsf << File.join(lp, rb) };
rbsf.each{|p| puts "#{File.basename(p)} = #{File.read(p).encoding.name}" };
puts "\n";

Reply with the results...

@tsur
Thanks for the update - so we can rule out an old Unicode /U glitch.
But what it might be otherwise is currently a rare mystery...

@gullfo

Thanks for the info - so it's probably not a Unicode /U issue ?
However, have you tried renaming your user-account in case ?
I'm assuming your Windows user-account name contains only ASCII characters and some limited punctuation, as instructed by Microsoft ? If you are unsure you can use the chat speech-bubble tool to PM it to me privately...

We are investigating this because there are thousands of users without this error, so we need to do some detective work...

@ntxdave
There's an Uninstall Manager dialog in the Extensions > SketchUcation submenu.
This renames the selected RB files RBX so that after a restart they no longer load, appear under the Plugins Manager dialog etc.
However, they are still there and can either be ignored, reinstalled using that manager, or manually deleted later.
To delete them open your Plugins folder and ensure that folder settings show file extensions.
Sort by Type so that all of the RBX files are together.
Delete them one at a time, noting the name so that you can also delete the associated folder - e.g. some_script1.rbx and its subfolder some_script1.
The Plugins folder is hidden by default - but there's a tool in the Extensions > SketchUcation submenu to open it for you...

Can you both please try the text in the Ruby Console I prepared earlier...
You are using different operating systems...
But one thing you both have in common is your user-name is in capitals and starts with a U.
I'm assuming you haven't edited the text you posted...
There were reports some time ago about this kind of issue.
SketchUp's Ruby can see the /U in a string as a Unicode escape character - and this breaks the UTF-8 text format it's hoping to be using... Not sure if lowercase /u has the same issues ? Hence the encoding error message at the start...

Can you try a change in your user-name to use all lowercase characters, or NO U after a / at all, restart your computer and try again ?
I'll look at ways of trapping this error, if it's possible...

@gullfo

This is a previously unknown, and so far inexplicable, error.

How many Plugins folders do you have set up ?
Do they all have .RB files in them ?

To find a list can you please do this:

Open SketchUp

Open Extensions > Developer > Ruby Console

Copy/paste this as one line:
puts "\nDefault:\n#{Sketchup.read_default("SCF", "DefaultPlugins", "???")}";lp=SCF_Dialog.getMyPluginsFolders();puts"\nAll:\n#{lp}\n\nContents:\n";lp.each{|p|puts Dir.entries(p).size-2 };puts"\nRBs:\n";lp.each{|p|rbs=[];Dir.entries(p).each{|f| rbs<<f if f=~/rb$/};p rbs.length};puts;

Press enter

Copy all of the returned lines and paste them into a reply.

@Jspro

You are NOT getting the properties of your *Plugins folder - that's the SketchUcation.RBZ !

In any case your user account was not highlighted in the dialogs that you snapped.

If that* was and has checked 'Full' [first item], even if it's 'greyed' it should be OK.

Can you please learn how to make PC based snapshots of your screen or dialogs without resorting to actual photographs - it makes reading this very awkward...

Late on in 2017 they changed the menus etc.
Preferences no longer linked you to Extensions.
The equivalent Extensions Manager then appeared under the Windows menu,
later on this migrated again - this time into the Extensions menu.
The Extension Manager has its own dedicated dialog,
with an Install Extension... button to do exactly what the earlier way did.

@Jspro
All or the files and subfolders in your plugins folder [path in the error messages] should have appropriate FULL permissions.
Try the following:
Select the 'plugins' folder's icon, right-click > 'properties', then 'security' tab, your user-name should be listed, choose the 'edit' button and ensure that you have 'full control' set up. Choose 'apply', then OK.

Our v5.0.1 is now published in the ExtensionStore.
This traps for sloppy extension creation without a version being set.
After you install that you can restart SketchUp, and then restart using InstantArchitecture without any clashes...