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Fortran 2020 Expression Evaluator causing Visual Studio to Crash


I'm using Intel Fortran2020 on WIndows10.  I've tried Visual Studio 2019 and 2017, same issues.  When debugging, all is well until you mouse over any array, at which point Visual Studio crashes.  When starting Visual Studio up again, the message is "A previous session terminated unexpectedly.  Disabling extension 'Intel(R) Fortran Expression Evaluator 20.0.21' might help prevent similar issues.  Disabling this is terrible, you can no longer see variable values unless you use the C notation in the watch window.  Not even sure that is working...

Visual Studio Professional 2017, 15.6.6  (I've tried VS 2019 as well)

Intel Parallel Studio XE 2020 Composer Edition for Fortran Windows* - Package ID: w_comp_lib_2020.0.166


I would think everyone is having this issue?  I did a search in the forum, didn't find anything...

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7 Replies
Black Belt Retired Employee

I haven't seen this myself. The interactions between the Fortran integration and Visual Studio are complex and obscure. My usual advice is to uninstall Intel Parallel Studio, reboot, then reinstall. In many cases this resolves problems such as this.

Honored Contributor II

McWilliams, Steve wrote:

.. I would think everyone is having this issue?  I did a search in the forum, didn't find anything...

The image below captured by hovering the mouse over an array in a debugger with Visual Studio 2019 and Intel Parallel Studio 2020 may not help, for it shows you not all installations have the problem you face.


That said, there are users in the teams I work with who have experienced similar issues.  Uninstalling and reinstalling, several times in some cases, has been the remedy but users are getting upset over this because it eats up a lot of time and causes considerable loss of productivity and so it's not acceptable as a cure.

So if you have Support included in your license, I suggest you contact and file an issue.

Valued Contributor II

I use VS 2019 Preview and the latest Fortran -- it works fine.  I would install the preview version and try it again. The two VS will live happily side by side



Thank you fellas for the comments.  Sorry for slow reply.  New world just recently...

After trying different versions of Visual Studio, and different flavors of that mess (enterprise, professional, community, who knows), I finally got the debugger to not crash when I went all the way back to VS2010 and Fortran2011.  WHich was what I was using in the 1st place.

Today, I think I found the solution to my problem with VS2019 and Fortran2020.  I deleted the solution and project files, and started from scratch.  Prior to this, I had just been building exe's using the same project/solution files that I've used for years.  Looking back, it seems I was kinda stupid to just keep on doing that.  Problem is, I don't really understand what's in those files in the first place.  At least, no exactly.  Things are now working, no crashes while debugging, I can stop and see variable values without issues.  So far, at least.

So, should other slow-thinking individuals post on the forum about this problem, tell them to delete existing project and solutions files, and then re-create them.

Black Belt

It would be interesting to know the difference between your project/solution files previously and now - what is it about the recreated files that means that they are not problematic.

There are other generated files within the solution/project directory structure that are used by Visual Studio (suo - solution user options) or the ifort integration (u2d - no idea) to store/cache stuff generated when building and running projects - if recreating the solution is helping, then I wonder whether there might be an issue with these files (you can delete them and they will be recreated, though Visual Studio will have become a bit absent minded about some of your preferences).


We are also experiencing this issue and it would be great if someone could determine why the above "fixes" fix it.

We have a very large (and very old) application with thousands of source files, both C++ and Fortran. We are using Visual Studio 2019 16.4.4 with Intel Fortran 2020. We compile C++ code with the Microsoft compiler. We also have 200 project files, so throwing those away and recreating them would be very costly, besides, our Fortran code is compiled via makefile projects, so there aren't a lot of relevant settings in those project files.

To try a partial "restart" and do as IanH suggested, I deleted the entire directory containing our source, project files, intermediate files, etc and then re-fetched the source from our version control system. I then did a full rebuild and attempted to debug our program. As soon as it hit the first breakpoint in Fortran, Visual Studio crashed... When restarted Visual Studio complained that the Fortran Expression Evaluator (version 20.0.21) had caused the problem. The only way to debug our Fortran code is by disabling FEE, which makes examining variables somewhere between difficult and impossible.

This issue is really costing us productivity. If there is anything I can do to provide more information, just let me know.


Black Belt Retired Employee

Recreating the project recreates the .suo hidden file that contains things such as debugger breakpoints. It could be that these sometimes trigger a problem. You can enable display of hidden files and delete the .suo and .u2d files (the latter don't seem to be a problem, though) - sometimes this helps.

If you continue to have a problem, file a formal report with Intel through the Online Service Center.