I ran into a weird issue. I was experimenting with TFS tasks and constructing VSIX files because I have been away for a little while. I started with an existing, open-source project (which had a vss-extension.json file) and slowly morphed it from what was there to what I want it. However, I found that, when it came time to change the name of the “publisher” field in the VSIX manifest and the “author” field in the task manifest, I would do an upload and, although the VSIX uploaded and installed perfectly fine, the tasks would not show up.

Things I tried:

• Using the publisher name off another project located in the Marketplace.
• Using *my* personal publisher name (I am registered in the Marketplace).
• Using a random string definitely not registered as an existing publisher.
• Using a second, different project and trying the same changes to the publisher name, just in case there was something magical about the publisher in the first one (Microsoft, incidentally). There were some implied correlations between the publisher names, project names, scopes, and/or targets, and, most of those started with “ms” and I didn’t know whether this was significant and the real issue.
• Since I was experiementing on an on-premise TFS 2015 instance colocated on my laptop, I cut my Internet connection and installed the VSIX of a brand-new project in order to determine whether it could run or if it potentially did publisher lookups against the Marketplace. The latter was not the case. It installed fine.

It turns out that, if you are going to change the publisher, you need to change the version as well. When you uninstall a VSIX, the TFS still remains polluted with prior knowledge of that VSIX and/or those tasks.