'raise UserError(_("Cannot upgrade module “%s”. It is not installed.", module.name))' should occur if module.state is not 'installed' or 'to upgrade' only. That being said, your module, probably really just isn't installed after all - so you may want to try that once more. There are so many ways things can go wrong, it's pretty much impossible to say what exactly is going on in your setup with the limited information provided.
You'll have to investigate the log file and check what is happening upon restarting Odoo (this is the time when your addons folders are read from the config and a broken path would usually be mentioned here, in case there is any). Then you want to investigate the log file upon actually trying to install and upgrade the module. This can also provide valuable insights. But, since the error message is quite specific, I still believe you're trying to Upgrade my_app from the Apps list view while it is simply not installed.

Also, creating the same post with even less information given wont help you get actual answers. This is a community forum and there is no obligation from anyone to work out other users issues. So, try to improve your post with information that could be relevant - specific information such as what your module structure is, what your manifest looks like, what your log says (but don't post thousands of lines of log entries) - and even basics such as your Odoo version, to begin with. See also https://www.odoo.com/forum/1/faq

i wanna thank you for replying to my post and for given me an advice for how i will workout my problem and about posting one more time it was just rookie mistake, i see post in 2/3 lines and i think i shouldn't say much and not given  much information for people to read, again i just start learning  so thank you again for help me do that