Cannot install J2Store Migration Checker

[krishunt]

If I drag the com_j2migrationchecker-v1.0.2.zip file to my drag-and-drop installation area, I get the message "Internal Server Error" in a red banner at the top of my Joomla back end. If I browse to the file to try and install it that way, I get a "This page isn't working" error.

I currently have J2Store 3.3.7 installed, so I thought maybe the problem is that I need to upgrade to 3.3.20 before I can install the Migration Checker. But when I try to update the extension, I get this error:

Failed to download package. Download it and install manually from https://www.j2store.org/download-j2store/j2store-v3-3-3-20/com_j2store_v3-3-3-20-pro.zip?format=raw&dummy=my.zip.

So I try to go to that URL, and I get a 404 error.

Every copy of J2Store version 3 seems to be gone from the internet. Please help.

[krishunt]

Never mind; I finally found where I can download old extensions in my account.