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I am seeing the same issue. Errors in Python code are not highlighted since latest VS update. Running a project (with or without debugging) causes the 'Launch with errors?' dialog to pup up, but there is no visual indication of where the error(s) actually are. Errors are not shown in the 'Error List' pane either, though VS clearly knows they are there somewhere!

@Steve Dower I cannot produce the log for a few days because I am out of town. But please note that this problem should be easily reproducible:

Simply install Windows 10, and then Install VS 2017 15.4 with python tools selected.

Create a new solution. Create a new python project "python_project". In the python_project.py script, type some nonsense (see? no error highlighting.) Now make another python project "other_module" in the same solution. Add "../other_module" to the Search Path for python_project. Now in python_project.py, try typing "import other_module". Intellisense will say "Cannot resolve 'other_module'" (see? no importing modules from other projects). There are probably other python Intellisense problems you can find in 15.4.

Also, this issue was raised again by another person who did not know about this thread:

https://developercommunity.visualstudio.com/content/problem/132688/ptvs-general-intellisense-problems-no-error-highli.html

I just did an upgrade of VS Pro from 15.4.0 to 15.4.1 and that broke python for me....My code now crashes with import ipdb File "C:\Program Files\Anaconda2\lib\site-packages\ipdb_init.py", line 7, in from ipdb.main import set_trace, post_mortem, pm, run # noqa File "C:\Program Files\Anaconda2\lib\site-packages\ipdb_main.py", line 27, in from IPython.terminal.debugger import TerminalPdb as Pdb File "C:\Program Files\Anaconda2\lib\site-packages\IPython_init.py", line 49, in from .terminal.embed import embed File "C:\Program Files\Anaconda2\lib\site-packages\IPython\terminal\embed.py", line 17, in from IPython.core.interactiveshell import DummyMod, InteractiveShell File "C:\Program Files\Anaconda2\lib\site-packages\IPython\core\interactiveshell.py", line 62, in from IPython.utils import io File "C:\Program Files\Anaconda2\lib\site-packages\IPython\utils\io.py", line 98, in stdout = IOStream(sys.stdout, fallback=devnull) File "C:\Program Files\Anaconda2\lib\site-packages\IPython\utils\io.py", line 43, in init_ val = getattr(stream, meth)NameError: global name 'channel' is not defined

Thank you for your feedback! We have fixed the problem in an upcoming release. Thank you for helping us build a better Visual Studio!

Today's VS 2017 Update to 15.4.2 fixes this problem. Thanks! I just now updated and retested, and the Python Intellisense issue is fixed. Also, you can reference my (so-called duplicate) issue at:

https://developercommunity.visualstudio.com/content/problem/140352/python-intellisense-is-limited.html

Good job on getting the error squiggles back. With the latest release, there is still the issue of "Intellisense not scraping modules from other projects", which was mentioned in this issue's links. Just now, I made a separate GitHub issue for it at https://github.com/Microsoft/PTVS/issues/3248

15.4.2 was supposed to fix Python Tools but my Visual Studio 2017 Enterprise is worse than at 15.4. When I add a new python file it creates a new file but the project does not see it. If I try and add it as an exisiting file after the fact, it says it already exists. Also the editor profile seemed to get messed up. My tab to spaces setting is all messed up and if I copy and paste it does odd indenting.

15.4.2 did not fix my issue on 2017 Enterprise. When I add a new python file to the project it creates the file but does not add it to the project. If I try to add it to the project as an existing file it says it already exists in the project, even though it doesnt show it. Also, my tabs to white spaces setting got messed up and now I get weird indents.

Sorry Steve, didn't read the comments first. Basically just installed latest update (15.4.2) and now debugging hangs, hollow breakpoint never hit. Same file start without debugging runs fine.