A tip for anyone trying to upload a different image for an already-published app. You need to unpublish it first, to make the "Upload image" option appear on the menu. See this GH issue comment.

A related tip is that when you send your unpublished-and-modified app for approval you can override the default next version number that appears in the dialog, setting it to the same as the current version. You'll still have to enter something in the Release Notes field, but when your changes are subsequently approved your published app won't show any change in the Version History tab.

We're not all dead yet! I still have a full set of MSM 4.4 printed documentation on my bookshelf. And several developers who worked for Micronetics are still on the staff at InterSystems (pinging @Chuck Sorenson)

I haven't tested this, but you may be able to use the ZFLUSH command to flush buffers to disk, after first setting switch 13 using D ^SWREG in the MGR UCI to disable database writes. SWREG has entrypoints to let you set and clear switches programmatically.

In case there are still some MSM experts out there who aren't on Developer Community, you might also try posting on https://groups.google.com/forum/#!forum/comp.lang.mumps

To use the debug features of Serenji you will need a keyfile issued by us at George James Software. Free evaluation keyfiles are available on request, normally lasting 30 days. On the Extensions section of VSCode, select the Serenji extension and follow the link in the "Installation" section to get full instructions.

I'm guessing you opened a CLS file that implements your API, which I assume is a REST one. For debugging we use InterSystems' native debug support, which operates on the INT code that your class compiles into. Depending on how you compile your class, that INT code might not have been retained. After all, it is "intermediate" code from which the runtime OBJ code gets generated. The documentation I pointed you to above explains how to keep INT code.

With Serenji VSCode's F9 key (Toggle Breakpoint) currently only operates when you are in an INT file. It's on our roadmap to add support for the setting of breakpoints in CLS source.

Also on our roadmap is the addition of a mechanism to let you debug the web gateway's server-side process that services your Postman request. Meanwhile you may be able to use Serenji's 'Existing Process' debug configuration to attach to the right server-side process, but it's challenging to pick the right one. Alternatively, use the 'ClassMethod' debug configuration and call directly the server-side classmethod that implements the method in your REST API.