Pokemon White 2 freezes when performing trades with NPCs

[Blazekickn]

What version of melonDS DS are you using?

v0.7.25

Does the problem happen in standalone melonDS?

I don't know.

What happened?

Using the Explorer Kit when playing the Pokemon Diamond Version Bonus subset crashes the game. Swapping to the normal rom it works as intended. (Both using the USA rom)

Performing an ingame trade in the Pokemon White 2 Professor Oak Challenge (in my case the Excadrill -> Ambipom trade) also crashed the game. I didn't test if the crash also happened in the normal rom but trades in the GTS seem to work fine on both roms.

Both issues were not present in other cores.

What should've happened instead?

Using the Explorer Kit in Diamond and Performing an ingame trade in White 2 should work regardless of which version used

Which platforms do you see the problem on?

• [X] Windows
• [ ] macOS
• [ ] Linux
• [ ] Android
• [ ] iOS
• [ ] tvOS
• [ ] Other (specify below)

Which versions of the OS?

Windows 10

Which libretro frontend are you using?

RetroArch 1.15.0

Terms

• [X] I agree to follow the code of conduct.
• [X] I understand that melonDS DS is not developed or maintained by the authors of melonDS.
• [X] I understand that this form is for reporting bugs, not for requesting help.
• [X] I understand that the author develops this core in his spare time, and that he is under no obligation to respond to this bug report.

[JesseTG]

It looks like these subset patches for RetroAchievements modify a single byte in the header, but without updating the checksum that's in the same header. I wonder if that trips up the game? Maybe I should experiment with a core option that forcibly recomputes the checksum, just to see if that fixes the issue. Could you post a save file (not a save state) so I can use it to reproduce this?

Also, does this behavior occur with the built-in BIOS/firmware? Or with native dumps? Or both?

[Blazekickn]

It looks like these subset patches for RetroAchievements modify a single byte in the header, but without updating the checksum that's in the same header. I wonder if that trips up the game? Maybe I should experiment with a core option that forcibly recomputes the checksum, just to see if that fixes the issue. Could you post a save file (not a save state) so I can use it to reproduce this?

Also, does this behavior occur with the built-in BIOS/firmware? Or with native dumps? Or both?

You should be able to access the underground anywhere outside a building using the Explorers Kit Key Item: Diamond Save File

Saved in front of the Mantine for Tangrowth trade with a Mantine in the party: White 2 Save File

These issues do not occur in the unmodified roms from my testing. Native vs. Built-In doesn't seem to change anything.

[JesseTG]

I cannot reproduce the issue in Diamond; the Explorer Kit works as expected both with and without the patch. Haven't tried the White 2 save yet.

Is it possible that these were fixed as part of the major refactor I finished? Could you try to reproduce these bugs with the latest build?

[JesseTG]

The game does freeze when trading the Pokemon in White 2 at the location in the save file. However, it occurs with and without the RetroAchievements patch.

[JesseTG]

The issue with White 2 occurs on standalone melonDS, commit 4b4239d, even without the RetroAchievements patch. You may want to comment on this ticket with any further information.

Since this issue occurs upstream, I encourage you to continue any discussion and troubleshooting there. However, this ticket will remain open until the linked one is resolved.

[Blazekickn]

I swear that i tried the trade and it worked, but i might've used a different core by accident. I'll test the explorers kit.

[Blazekickn]

can confirm explorers kit works on the latest update 👍