If it works in v2024 [see earlier posts] it'll probably work in v2026.
Try it.
To install an extension from a ZIP archive file rather than from an RBZ you will need either to change the file-type suffix, or even easier use the SketchUcation submenu item to install it from Archive, which works for both RBZ and ZIP archives...

The current LibFredo6 works with all recent versions of Sketchup.
There is also a legacy version in the PluginStore for older versions - i.e. <= v2016

What are 'the error messages' ?
A BugSplat or something else ?
What is your MAC OS ?

Select its icon and right-click > context-menu > Run as administrator.
A dialog opens, when prompted choose Repair.
This will fix any incorrect permissions etc that can cause unpredictable issue.
Restart SketchUp to see if anything has improved.
Repair will not affect any customization.
Double-clicking

@euljoo
Did you check your spam folder ?
Did you check https://sketchucation.com/webshop/my-licences.php ?
This lets you download copies of any license-files you have purchased.
After downloading a file to somewhere safe you can then validate it in the appropriate tool's menu item.

Version 5.0.6 is now available:
https://sketchucation.com/pluginstore?pln=SketchUcationTools

It's trapped for a very rare error [only one report to date!] which splatted the tool on loading, when it was checking an extension's version for the update report - if the user's installation of that extension's files is somehow incomplete - perhaps because of the use of su's migrate tool across versions glitch ? [Note: this principally affected just some of Fredo's and perhaps Thomthom's extensions, where Extension-Manager then lists it without a version etc and they were unloaded in the PluginsManager]

@rlgl

The error is currently a mystery to me.

It's showing an error for a missing file -
C:/Users/dvnj2/AppData/Roaming/SketchUp/SketchUp 2026/SketchUp/Plugins/Fredo6_FredoSection/FredoSection.plugin

Checking I see that I do not get the same error message - everything works fine.
AND I also see that the .plugin file does exists in my Plugins folder.
If an extension is not loaded [when its version would be readily findable],
then because the version is not immediately got the ExtensionStore in checking your current extensions' versions has to try and get them in other ways.
A version is usually readable from an extension's registration xxx.RB file - even if it's been disabled using our Plugins-Manager.
But a couple of authors - like @fredo6 - don't set the version in that file,
but use a unique hash system to read their settings in from a xxx.plugin text file, kept in each extension's subfolder.
To the best of my knowledge all of Fredo's extensions use this method, as does this one.

I can force the same SketchUcation error as yours, by manually removing the FredoSection.plugin from its subfolder.

There are two cases:

1. FredoSection is set to be loaded in the PluginsManager - this error is sidestepped because the FredoSection extension is enabled in the Extension-Manager and its version is readable from the its properties. However, the Extension' properties all report as empty, and so no version etc could be read in. In this case the ExtensionStore defaults to thinking it's '0' and ignores its version.

2. FredoSection is set to be unloaded in the PluginsManager - this error is then thrown because the FredoSection extension is not now enabled in the Extension-Manager and its version is not readable from the its properties AND the .plugin file that would otherwise return the version is also not found. The error prevents the ExtensionStore from completing its version checking. This error could be sidestepped, but them you don't find out there's an issue with your FredoSection setup.

So this suggests to me that your installation of FredoSection extension is incomplete and the ../Fredo6_FredoSection/FredoSection.plugin is missing,
If you were not using the SketchUcation extension at all you would not get an error at startup, but just empty details in the ExtensionManager listing.
How did you install the FredoSection extension ?
If you have somehow copied files/folders from another Plugins folder this might have missed out vital files. Manual copying and the new su 'migration' tools can cause weirdness...

Please try reinstalling the extension and checking that ../Plugins/Fredo6_FredoSection/FredoSection.plugin file now exists, and the SketchUcation extension loads OK.
You can install from its RBZ using the Extension-Manager, download it from our PluginStore.
Alternatively you can close SketchUp, and find the file:
C:/Users/dvnj2/AppData/Roaming/SketchUp/SketchUp 2026/SketchUp/Plugins/Fredo6_FredoSection.rb!
and rename it as:
C:/Users/dvnj2/AppData/Roaming/SketchUp/SketchUp 2026/SketchUp/Plugins/Fredo6_FredoSection.rb
i.e. without the ! at the end which was added to disable it.
After a restart this will allow SketchUcation's ExtensionStore to load and you can now use its dialog to reinstall the FredoSection extension, rather than using an RBZ.
See if the FredoSection.plugin file is installed properly and so on, and the the Extension-Manager now reports its proper details like author and version.
To stop even the currently faulty FredoSection file set from partially loading and tripping up the ExtensionStore you can use the Extension-Manager to disable the extension, rather than use the PluginManager.
A very remote possibility - if the .plugin file does indeed exist, but SketchUp can't find it, perhaps it is for some reason unreadable - so check its Security Properties.

The 'require' code that is unneeded doesn't break anything, just takes a millisecond to process and immediately ignore, slowing the loading time all but imperceptibly...

Have a good day too...

Thanks for the upload to the PluginStore/ExtensionStore.
I have Published it for you, so it's now available to all users.
I can see little to comment on - it works fine.
Note that require 'sketchup.rb' etc is not needed in any of your code, because, unlike older versions, it's now auto-required at startup as SketchUp loads, before your scripts are considered.

It's almost certainly OK on v2026 as far as it did with recent versions already - which was 'not faultlessly'.
But why not try it...

It is very old, but it works with v2026.
BUT there are several 'reverse face' tools available that are newer, less flaky, and probably better...
e.g. my own 'Fix Reversed Face Materials' which flips faces textured on their backs and reapplies the material, UV-mapping any textures to suit, and includes several other subitem tools to adjust reversed faces and their materials...

One further issue you should address before publishing this more widely - e.g. getting it 'signed' and in the EWH.
Its file naming does not follow the proper conventions.
An RBZ must contain just one .RB file that registers the extension and a folder of the exact same name.
Also the convention is to prepend the users 'name' at the start and even a sub-level if the modules do this.
So in your case there should be MendelAI_mesh_tools subfolder and a .RB file named MendelAI_mesh_tools.rb
You then edit the RB to load MendelAI_mesh_tools/loader

Because previous users might also now have the older badly named file/folder installer and loading you need to do some tidying up.
Add some code to the start of the RB to check for the existence of mesh_tools_loader.rb and mesh_tools subfolder in the Plugins folder -
use File.exist?(str) or better still similar methods in the fileutilities [which you need to 'require'] which will make deleting the subfolder and its contents much easier. So if these files exist you should also add a UI.message_box() to ask the user to restart to sync everything - next time the rogue file/folder won't be found and the code is redundant, but is still needed in any future updates in case a user has skipped this change in 1.0.2... A manual restart is preferable to a forced quit etc as the user might not have saved some work before updating etc.

@ntxdave
Showing back-edges can be useful in some modelling and presentations.
It's default View shortcut is K, but you can also toggled on/off in the Style dialog.

If you have accidentally pressed K then back-edges might be 'on'.
Try pressing K again to toggle them 'off' ...

I think you've trapped almost everything.

However in the self.loop_dynamic_purge_ghost_material method you look at ent and then manipulate its material if it's a face or a group or a component-instance.
But if those are no longer valid for some reason [I do suspect that could be an incredibly rare chance?] then it could throw an error and fall over.
A simple check at the start of the method's do-block that is searching through the model.entities e.g.
next unless ent.valid?
skips any invalid ent

Incidentally, without analyzing the whole code-set, firstly why not use model.active_entities which potentially reduces the list length, and secondly what about any faces within nested groups etc not inspected by this method that might still have that material ?

Works well.

But I have a few observations from a non-AI view-point...

The Dynamic_Subdivide.rb file uses several $xxx... global variables - these are frowned upon because they can pollute all other Ruby files [and are not acceptable in extensions submitted for review in the EWH].
It's a simple fix - replace them all with @xxx... variables that then work across methods in the same modules, but not 'globally' in unconnected scripts.

That Dynamic_Subdivide.rb file also has potential trip-hazards as Rich pointed out -
e.g. in line#190 it's possible for it to reference an edge of a face that is no longer valid, as specified in an earlier line, so it falls over.
This not valid issue occurs when your operation does something to geometry that affects a previously made collection of things -
e.g. adding a new face [or edge] overwrites an existing face [or edge] so a reference to it is no longer valid.
Again it's a simple fix - add a 'skip' trap near the start of the block -
e.g. like this
faces.each do |face| next unless face.valid? ... end
which skips any invalid faces and so the errors are sidestepped.
You can do a 'find' in the code to add in similar traps like this for any non-valid face, edge, vertex etc.
Also note that the various blocks have an inconsistent format, swapping between
xxx.each { |e| ...xxx... }
to
xxx.each do |e| ...xxx... end
But editing either of them is possible with a little care.
Both forms are acceptable, but choosing to use just one for consistency is recommended...

@zmd
Also make sure you have the latest SketchUcation toolset installed for the licensing etc [>=5.0.5], it's version is shown in the top bar of its dialog.
If you update it restart SketchUp to sync everything...
As well as the latest versions of Fredo's extensions ensure you have his latest LibFredo6 too...
PS. Don't confuse Fredo's RoundCorner and FredoCorner extensions, they are separate tools, each needing their own license...
PPS. The current toolset requires >v2017 - what's yours ?

@DOUGLAS0712

His tools are no longer supported.
Sadly he died some time ago...

Suas ferramentas não são mais suportadas.
Infelizmente, ele faleceu há algum tempo...

I'm sure @fredo6 will have more to say...
but the report your posted shows that although you have the latest versions of the 4 extensions installed,
you don't have the SketchUcation toolset installed - for the ExtensionStore and the required SCFLicensing files.
Without those all licensed extensions will not work.
Download the RBZ for the SketchUcation tools and use the Extension Manager dialog's Install... button.
Restart SketchUp to sync everything.
Now you will have the licensing set up.
You need to validate appropriate licenses for the 4 fredo extensions.
If you already have those use them, or get them from the appropriate page on this forum.
If you haven't already got a license then buy it.
Restart SketchUp after all of this to sync everything...

@SunnyGee2017
Thanks, that might be helpful...
Now up to @fredo6

@SunnyGee2017
I think @fredo6 will need more details before he can fully look into the cause...
e.g.
Are there any error messages in the Ruby Console or message-boxes ?
What kind of 'crash' is it ?
If it's a BugSplat then what are its details, and have you send these reports into SketchUp ?