How to fix certain swaps made broken by C.Viper Patch (15th October 2025)

FYI, this guide can only be used for swaps that are broken because the "esf0xx_0yy_01_chain.user.2" file get updated by C.Viper Patch. The list of affected characters are Ed C2, Elena C1, M.Bison C1, Mai C1, Mai C3 and Manon C4; so if the not working swap is from these listed affected characters, you can try using this guide to fix it.

How to identify whether the swap is from which character, you ask? You can either look at the swap mod name (eg. "Mai C1 swap to XXX" meaning the source is from Mai C1) or if the swap mod name is not clear enough (eg. "Mai Curvy Bikini (by timetravel80) swap to XXX") then you can look at the BASE FILES (eg. in the modinfo.ini of that Mai Curvy Bikini swap its description line says "!BASE: Mai C1 ORIGINAL TEXTURE FILES", that means the source is from Mai C1).

Okay, now that the identifying process is done, I will now write the step-by-step process of how to easily fix the broken swap mod by yourself.

1. For the purpose of the guide, I will use the "Mai_C1_swap_to_Jamie_C1" as the example. Extract the "Mai C1 swap to Blanka-DeeJay-Ed-Guile-Jamie C1.rar" to somewhere (preferable with short path, for example: C:\) and browse thru the "\Mai_C1_swap_to_Jamie_C1\natives\STM\Product\Model\esf\esf021\001" folder to see there is a file with name "esf028_001_01_chain.user.2".

2. Next, please download the "CViperPatch_ChainUserFiles.rar" from my MEGA drive, extract it to somewhere (for example: C:\) and you will see that I have categorized the folder based on the affected characters. And since we have identified the source is from Mai C1, so browse thru the "\Mai C1\natives\STM\Product\Model\esf\esf028\001" folder to see there is also a file with same name "esf028_001_01_chain.user.2".

3. Copy the "esf028_001_01_chain.user.2" from "\Mai C1\natives\STM\Product\Model\esf\esf028\001" folder and paste it to the "\Mai_C1_swap_to_Jamie_C1\natives\STM\Product\Model\esf\esf021\001" folder. Overwrite or replace the existing file when asked.

4. Now to continue, you will need a hex-editor program. Any program will do but for the purpose of this guide I will use the freeware "HxD" (download it from here). Open the "esf028_001_01_chain.user.2" from "\Mai_C1_swap_to_Jamie_C1\natives\STM\Product\Model\esf\esf021\001" folder with HxD.

5. Press Ctrl+R (on your keyboard) to see the "Replace" dialog box. From there, do the following things carefully:
a. In the "Search for" box, type Product/Model/esf/esf028/001 (the underlined folder path from step #2).
b. In the "Replace with" box, type Product/Model/esf/esf021/001 (the underlined folder path from step #1).
c. --VERY VERY IMPORTANT-- In the "Text encoding" dropdown box, select the "Unicode (UTF-16 little endian)" --VERY VERY IMPORTANT--
d. Click the "Replace all" button and you should see the message box which says like "Replace 2 occurrences of "Product/Model/esf/esf028/001"".
e. The hex-editing is done, don't forget to save the file by pressing Ctrl+S (on your keyboard) and close the program.
f. --OPTIONAL-- HxD creates a backup of the edited file, so if you are 100% sure that you don't do any mistake during the hex-editing process, you can delete the "esf028_001_01_chain.user.2.bak" file, otherwise there is no harm to leave the backup file in there. --OPTIONAL--

6. You can now testing the fixed swap mod by installing it with FMM (I don't need to tell you how to do it, right?).

7. All done, and congratulation for fixing the swap mod by yourself :)