Hi,

I am experiencing some strange behavior with VM after upgrading from 2021.106 (I think; from memory) to 2021.6060.0. 
After the upgrade I cloned an existing project to create a new version. 
The new version compiled fine once. 
After making a couple of tiny changes, I compiled again and got a Segmentation Fault error - for a library unrelated to the change.
Closed and reopened VM solution - no change.
Closed VM and rebooted - Now the project isn't recognized as an Arduino project by VS - there are no build options on the ribbon.
I see the same behavior for the previous working version - ie no build options on the ribbon. 
If I create a new Arduino project, the build options appear - but disappear when I switch back to the an existing project.

File names of the folder, project and .ino file are all the same.

Any suggestions would be much appreciated.

Thomas

Many thanks for quick response. 

Project zipped and sent.
Email subject line is the same as this one.

Best

Thomas

Therein lies the problem. Verbose and Show Build Properties are both checked, but there is no Compile button on the ribbon as the project is no longer recognized as an Arduino project by VM. See screen shot attached.

I just checked this again on another machine with the (an) older version of VM (2.21.106.19330). The known working previous version (306) of the project opens and compiles. The new cloned version (307) of the project that I emailed to you, opens, is recognized and can be compiled but throws the same Segmentation Fault error.
So something is off with the cloned version that I emailed to you.

This does not explain why neither old nor new project is recognized / can be compiled by the up to date install of VM on the machine I am having the issue with.

Many thanks

Now I'm even more confused. I have changed nothing other than to open up VM on the other machine and attempted to compile.

When I created a test project before in the same solution it would have the complete ribbon. However, if I reopen the test project after restarting VS, the ribbon options are no longer there. 
So I created a second test project [vMicro> New Arduino Project] and that makes the ribbon appear. AND this time, it stays there when I switch back to my projects 307 or 306. AND 307 compiles correctly.

This is repeatable. After restarting VS, the ribbon is gone again and only comes back if I create a new project. AND  307 still compiles.

In answer to your other questions:

Switching the build configuration to x86 (Win32 is not available) does not have any effect.

Get Tools and Features requires an update to the VS Installer before I can proceed. I will not do this yet.

Config manager 1/3

VS Help > About

Active Code HAS Priority Over Solution Explorer is checked.

What I said before is incorrect. My mistake. 
Creating a new project does not solve the issue, even temporarily. Test projects (only those created since VS was last restarted?), when selected in the solution explorer, cause the ribbon to display and can be compiled. The ribbon disappears when either 306 or 307 are selected in the Solution Explorer.

I had had a similar idea and just tested this:

Using the OLD version of VM (2.21.106.19330) I created a new Solution and added only the previous working project version (306) to it.
I then cloned the project:
  File > New > Project > Arduino Project
  Copy files from old project folder to the new project folder in Windows
  Add copied files to the project: Solution Explorer > Add Existing Item
  Copy code from previous Main to new Main.

I then created a new Solution on the machine with the up-to-date VM install and added the newly cloned project to that Solution. 

Both Solutions + Project now seem to be working correctly on both machines though this has not been extensively tested.

I notice that the Solution Platform is now x86 on both installs. This was not the case before - the up-to-date VM machine showed x64.

... and yes, opening the Projects in their own Solutions in VM 2021.606.0 also works correctly. So, as you suggest, this seems to point to some problem with the previous Solution File (which admittedly had a lot of baggage).

I kept some recent versions and R&D code in the same Solution for convenience. It had not been an issue until now.

I think that this is due to accessing the same Solution file from two machines - home and office... 

I have been storing code in the cloud and compiling in both places. I realize that this is what GIT is for, but I didn't think it was necessary. Am I wrong?

I do not know whether or not the issue with the previous Solution was caused by the x64 Solution Platform. I did not (knowingly) add a x64/non C++ to the Solution - only the clone of the previous project made after updating VM. 

I will repeat the cloning process on the of VM .606 and see if the problem reoccurs.

In any case, it seems that issue is resolved.

Many thanks for your help