No need to be defiant but definitely do create backups. 
Hello, Can you help please? I also got the “unexpected file format” message with nothing in the file. I tried renaming and changing the SKB to SKP but got the same issue. I am attaching the original SKP file here. Many thanks in advance for your help.
Coloured Elevs (1).skp (12.1 MB)
Which version of SketchUp 2023 are you using? Presumably ot the last release. Upgrade to that version of to SketchUp 2024 and you should be able to open the file.
Thank you for replying so soon, I shall do that
Do I need to uninstall the current version first? Thank you
No. But when you get ready to run the install, close SketchUp and LayOut. Then right click on the installer and choose Run as administrator.
There’s a bad group in the model which is responsible for your problem. The later release of 2023 and SU2024 will trap it and delete it. I also purged unused stuff from your model.
Coloured Elevs purged.skp (6.0 MB)
Thank you so much for your help.
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I managed the one you fixed, but will also download the latest version. So grateful to you! Many many thanks!
Hi @colin
I have the same issue here
I tried open the SKB and SKP file but got the same issue. I am attaching the original SKP file here. Many thanks in advance for your help.
nha Mr Hung rev2.skp
your file opens, but as read only.
you have a LOT of trash.
purge. just purge, every day, every week, go to model info / statistics and purge.
purging made the file shed 300mb
you have some huge materials. anything above 4000px is useless. and having the texture for oranges be 2752x998 is kinda useless. you’re modelling a house, not an orange.
Using Material Resizer (free extension) allows you to resize materials on the fly.
CG impact report (another free extension) shows me that you have a lot of leaves and curtains. they represent about a million entities.
if Sketchup is slow when you work on it, try turning off the vegetation and curtain tags.
https://www.swisstransfer.com/d/57e78024-9249-4dc6-a212-195695bc95cd
try this one and tell me if it opens fine
edit : also your profile says free plan 2024. there is no free 2024, it’s a pro 2024 free trial at best. or a crack. please correct your profile 
Dear @ateliernab
Thanks you for your support
When I opened your file, the error still hasn’t been fixed, the error is still the same “unexpected file format” Yes, I will update to correct my profile
Thanks you so much
well I don’t know what else I can do for you…
I downloaded from the link I gave you, and it’s opening fine.
are you running an antivirus that could alter the file ?
can you check the file on a friend’s machine ?
edit : hmmm, on PC it takes a long time to open, but still, it works.
Dear @ateliernab
Yes, I will try on other PC to check
Thanks you so much
Dear @ateliernab
I fixed the error on my computer because my computer did not have enough memory to open the sketchup file
Thanks you so much for your support
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Hi, Can anyone help me on my crashed sketchup file?
It happened after I turned off the computer and turn on again.
I have been working on this file for 2 weeks+ and I have unfortunately turned off the autosave so no file can be used for recovery.
Please help me on this 
The file can be downloaded from the link below:
Have you got the backup file (.SKB)? Unless you have disabled that too, SketchUp saves your older version of the model into a SKB file every time you save. This function is independent of the Autosave feature.
That file is missing a lot of data. Autosave is different than backup, even if autosave is turned off, there may be the SKB file that Anssi asked about.