I am using GD32C103CBT6 and platformio/tool-jlink does not support these since Segger only added them yesterday.
Well, and of course Segger added a lot of other interesting things since 7.50.
I manually updated .platformio\packages\tool-jlink with the files from my V770a installation and this works fine, I am only “afraid” that PIO will “update” it back to 1.75001. 
Huh. With my GitHub - CommunityGD32Cores/platform-gd32: PlatformIO platform for ARM-based GD32{F,E,L,W} chips. Work in Progress! platform or how do you put that in PlatformIO?
Btw, if you manually download the latest Segger JLink release, put the package.json from https://dl.registry.platformio.org/download/platformio/tool/tool-jlink/1.75001.0/tool-jlink-windows_x86-1.75001.0.tar.gz in it (with updated version string) and add
platform_packages =
tool-jlink@symlink://<full path to extracted JLink folder>
in the platformio.ini of the project it should work.
Yes of course, since you added it back in June after my request.
Only JLink did not directly support it, I was using GD32E103CB to upload.
I did not clear out the directory, it’s still in there.
And while this is working for me I just thought it might be a good idea in general to update the package. It does not seem to have a repository though and there is no author for it.
Absolutely, update would be good. I filed the issue in Update tool-jlink · Issue #643 · platformio/platform-ststm32 · GitHub as the closest match.
Done, thanks for the request!
Thank you!
I renamed the folder tool-jlink to check if the package is updated.
And it actually was not, but PIO was using J-Link Commander V7.70a regardless.
Only after I added
platform_packages = platformio/tool-jlink@^1.77001.0
the new package was downloaded.
Does PIO use the installed version if tool-jlink is not present?
Remove installed tool-jlink packages, run pio system prune command, and try again. It is a cache.
I’ve also updated Update JLink (better GD32 support) · CommunityGD32Cores/platform-gd32@fe80fcd · GitHub, so if you open a CLI and do a
pio pkg update -g -p "https://github.com/CommunityGD32Cores/platform-gd32.git"
you should have if with no need to specify platform_packages.
Hmm, interesting, I did run “pio system prune” and I did update the GD32 package.
However, renaming the tool-jlink does nothing, it just works and is not downloaded again.
Moving the tool-jlink folder out of .platformio\packages or plain deleting it has the desired effect though, the package is downloaded again.
Whatever this is - this is not an issue.