silenlin I tried running 3.8.99 on both a Mac PC and a Windows PC and could not reproduce the same problem. For reference, could you tell me what you were doing before you encountered this problem? 3.8.99 is an old version, so I assume that you have probably been using this editor for some time, but after replacing your PC or something, you were no longer able to start it? Did you have this problem on a PC that originally ran 3.8.99 without problems?

silenlin Thanks for showing the video! However, the video showed your license information as it was, so I removed it after watching the video in its entirety.
I couldn't tell for sure because of the Chinese interface, but maybe you are using a VM? There was a problem with older versions that required activation every time you tried to run Spine on a VM. (This is fixed in later versions.) And when accessing from China, the connection to our license server tends to fail frequently, which may be why running Spine 3.8.99 sometimes fails and sometimes succeeds. We recommend that you do not use VMs when launching older versions.

silenlin I see, so could you answer the first question I asked?:

Did you have this problem on a PC that originally ran 3.8.99 without problems?

silenlin Thank you for explaining your situation. You mentioned that you have been having problems starting 3.8.99 for some time, but I hope you understand that this version is actually quite old and that we are not able to make any fixes to it, even if we have confirmed that there are problems. The only thing we can do to make the editor work properly on the new PCs is to release a new version of the editor.

I suspect that 3.8.99 is no longer running properly, perhaps because you have updated some software installed on your PC, installed some new software, or removed some existing software. Do you have any idea what you have done?

Spine's launcher is 64-bit. Spine editor versions below 4.0 are 32-bit. If you choose a version < 4.0 then when you click Start the launcher starts a different executable, launcher\1\Spine-1.exe, which is a 32-bit program. Have you also excluded that executable from the antivirus and similar software?

Your log shows a VerifyError when Spine tries to read some of its files, meaning it found the files to be invalid. The files are stored in the C:\Users\brodee\Spine\updates\3.8.99 update file, so if something modified that file it could cause this problem.

The launcher deleted the 3.8.99 file and downloaded a new one. It then ran the 3.8.99 editor and got the other error, EXCEPTION_ACCESS_VIOLATION, which just means something terrible happened (memory was accessed where it shouldn't be). Unfortunately there are many reasons that could happen, so this doesn't provide any clues.

That it works sometimes is strange. My best guess is that something modifies Spine's files on your computer. Do you prevent your antivirus from messing with C:\Users\brodee\Spine\updates\? I suggest removing the antivirus completely (not just disabling) to see if it is the cause.

Please also exclude the files in C:\Program Files\Spine\launcher\1. This folder contains the executables responsible for running Spine versions < 4.0.

Additionally, you could do a RAM test. Since the error is not entirely deterministic, it might indicate a faulty RAM stick.

You also should exclude C:\Users\brodee\Spine\updates.

Uninstall the antivirus (not just disable or turn off) and see if Spine works. If so then you know the antivirus is not configured correctly.