The correct swap procedure (Windows)

1. Wait for the game’s own “please insert disc 2” prompt (or the save point at the disc boundary — most RPGs let you save first; do that).
2. Press Esc to return to the ePSXe window without closing the emulator.
3. Use File > Change Disc and point it at the next disc’s image (ISO, BIN/CUE or CHD).
4. Return to the game and confirm the prompt. The game should continue from the same session — your memory card save is the safety net if anything goes wrong.

Rules that prevent 90% of swap failures

• Same game, same region, same rip set. A disc 2 from a different release or region may have a different game ID and be rejected. Rip all discs from your own set (see ripping guide) and keep them in one folder.
• Never swap from a save state made mid-prompt unless you must. States capture the exact machine state; swapping discs around a state can confuse the game. Prefer the memory-card save at the boundary, then swap in a live session.
• Do not reset. Resetting and booting disc 2 cold works only for games that offer a disc-2 start via a memory card save — which most do at boundaries, but the in-session swap is the intended path.

Android disc swaps

The Android app handles disc changes through its own menu while the game runs; the 2.0.18 Android update fixed changedisc behaviour for several games, and the current 2.0.19 series is the one to be on — update in Google Play if swaps fail. Keep every disc image in the same folder the app can access (scoped storage), or the file picker simply won’t see disc 2.

Game-specific notes

Metal Gear Solid’s Special Missions disc-swap was specifically patched in Windows v2.0.18 — if you are still on 2.0.5, update before troubleshooting further. Valkyrie Profile and several other swap-sensitive titles are covered in our game-specific fixes. If a swap fails repeatedly with a verified same-set rip, loading the boundary memory-card save on disc 2 directly is the fallback that works for most RPGs.

Symptom: ePSXe doesn’t see the pad at all

• Plug in before launch. Connect the controller first, then start ePSXe. Pads connected mid-session are the single most common cause.
• Check Windows sees it: joy.cpl should list the pad and respond. If Windows can’t see it, ePSXe can’t either — fix the connection/driver layer first.
• Another app owns it: Steam (or another emulator) running in the background can intercept pads. Close them and relaunch ePSXe.
• Bluetooth asleep: wake the pad and confirm it is connected, not merely paired, before opening the emulator.

Symptom: works in menus, dead in game

The game is reading a different port or pad type than you configured. In Config > Gamepad, make sure Port 1 > Pad 1 holds your mapping (most games read Port 1), and match the pad type to the game: early PS1 titles expect a Digital pad and ignore analog sticks entirely; DualShock-era games want the DualShock type with analog enabled. Full mapping walk-through: controller setup guide.

Symptom: buttons wrong or swapped

Re-map in the config screen by clicking each input and pressing the physical control — do not trust a profile inherited from another emulator. One legacy quirk: v2.0.5 swapped the XInput vibration actuators to match the real PSX left/right, so a rumble that feels mirrored on an old profile is a profile problem, not a pad problem.

Android checks

• Pair in Android’s Bluetooth settings before opening the app, then map under Preferences.
• If the touchscreen pad appears over your game, your external pad profile isn’t active — select it in the input settings.
• USB pads through an OTG adapter need the adapter to support data, not just charging.
• For split-screen multiplayer, each player needs their own pad mapped to their own port — see multiplayer guide.

If the pad works in joy.cpl, is connected before launch, mapped on Port 1 with the right pad type — and still fails in one game only — suspect the game: a small number of titles read the controller in unusual ways and dislike specific pad types. Test a second game before rebuilding your whole configuration.

1. Use the internal SPU core

Set Config > Sound to ePSXe’s internal SPU core. The desktop releases have steadily improved it — v2.0.18 specifically reworked SPUCORE reverb and volume handling, with fixes audible in games like Ghost in the Shell, Dino Crisis 1 & 2 and Wipeout. Old external SPU plugins are the most common crackle source on current builds.

2. Stabilise the frame rate first

If the game itself stutters or runs uncapped, the audio will crackle no matter what the sound settings say. Lock the frame limit (our too-fast fix covers the settings), and if your PC is struggling at high internal resolution, lower it one step — a stable 60 fps at 2x sounds better than a wavering 60 at 4x. On a weak machine, the software renderer is often the cure; see ePSXe on a low-end PC.

3. Latency and mode options

• Try the SPU core’s latency/Async options: a slightly higher latency setting trades a few milliseconds for clean sound on machines that crackle at the lowest setting.
• Keep XA sound enabled — disabling it silences music in many games and can masquerade as an audio bug.
• Bluetooth headphones on Windows add their own delay; if sound is clean on speakers but late on Bluetooth, that’s the headset path, not ePSXe.

Android: switch to the Oboe engine

v2.0.19 added the Oboe sound engine specifically to cut audio latency on Android — select it in the sound preferences. If crackling arrived with the 2.0.19 update itself, note that the team shipped SPU regression fixes in the 2.0.19.x point releases, so update the app in Google Play before deep-diving settings. Persistent Android audio trouble after that: lower the internal resolution, close background apps, and re-check with wired audio to separate device limits from emulator behaviour.

The quick toggle: F4

While a game runs, press F4 — it toggles the frame limit in ePSXe’s core sound/config options. If the game immediately settles to normal speed, the limiter was off, and you have found the culprit. Leave it on.

Set it properly in the video plugin

1. Open Config > Video > Configure for your active plugin.
2. Enable Use FPS limit and set the limit to Auto (or 60 for NTSC / 50 for PAL games).
3. Make sure you are not running two limiters fighting each other — the plugin limiter or an external one (a GPU driver frame cap can stay, but an emulator plugin and an overlay tool both limiting can cause judder).

Still too fast — or now too uneven?

• High-refresh monitors: with V-Sync off and the limiter misconfigured, ePSXe can sync to a 144 Hz panel instead of the game’s rate. The limiter, not V-Sync, is the authority — set it explicitly.
• Speeding up only in menus: some games run uncapped in specific screens when framebuffer settings are off; this is cosmetic and normal for those titles.
• Android: check the frame limit / FPS options in Preferences; an accidental turbo/fast-forward state is usually a mapped hotkey on the gamepad profile. See the Android setup guide.
• Sound racing with the picture: that confirms the whole emulation is uncapped, not just the display — the limiter fixes both, and persistent audio weirdness after that belongs to the audio fix.

One warning in the other direction: a game running at a locked, correct speed on original hardware also had slowdown. ePSXe at 60 fps with the limiter on reproduces the game as designed — don’t chase “faster than real” as a goal outside the built-in fast-forward moments.

The fix: change the CD-ROM core

1. Open Config > CD-ROM.
2. Select the internal ePSXe CDR WNT/W2K core (the Windows NT-line core) instead of any ASPI option.
3. Restart ePSXe and load your game image (File > Run ISO) as usual.

That is the entire fix for image-based play, which is how almost everyone uses ePSXe today: BIN/CUE, ISO, IMG, PBP or CHD files ripped from their own discs.

Why this error exists at all

In the 1.x era, reading original discs through ASPI was a normal path, and old configuration guides still circulate. If your ePSXe configuration was copied from such a guide — or your install is a layered upgrade of a very old folder — the ASPI setting can survive into a modern Windows that has no ASPI layer. A clean v2.0.18 install (verified against the checksum on our download page) defaults sensibly and never asks for the file.

Do not download wnaspi32.dll

As with zlib1.dll, standalone DLL sites are not a safe source, and forcing an XP-era driver layer onto Windows 10/11 can destabilise the whole system for the sake of one setting. If you genuinely play from original discs in a physical drive, the internal core handles modern drives; if it cannot see your drive, that is a drive/firmware issue, not an ASPI one.

The clean fix: reinstall from the official package

1. Delete the folder your current copy lives in (keep your memcards and sstates folders — copy them aside first).
2. Download the current Windows package, ePSXe2018.zip, from the official source via our download page and verify the SHA-256 printed there.
3. Extract the entire zip to a fresh folder and run ePSXe.exe from the extracted folder — never from the zip preview. Most zlib1.dll reports come from running a partially extracted copy or bolting a new .exe onto an ancient folder.
4. Copy your memcards and sstates back in.

What not to do

Do not download a lone zlib1.dll from a DLL-download site. Those sites are a classic malware vector, the version is a lottery, and dropping random DLLs next to the .exe masks the real problem: a mixed-up install. If an error names a system library, the professional fix is a clean application folder, not a file hunt.

If the error survives a clean install

• Check which component asks for it: if ePSXe opens but the error appears when a specific old external plugin loads, that plugin is the stale piece — switch to the internal core plugins (see how the plugin system works).
• Confirm you are on the 32-bit program’s terms: ePSXe 2.0.18 is a 32-bit executable, which runs fine on 64-bit Windows, but 64-bit plugin DLLs from other sources will not load into it.
• Re-extract with a different archiver if files arrive incomplete; a truncated zip explains several of these legacy errors at once, including the wnaspi32.dll one.

Why ePSXe asks for a BIOS at all

The BIOS is the console’s built-in firmware. ePSXe emulates the hardware around it, but most games call BIOS routines to boot, read discs and manage memory cards. The readme in the official ePSXe package states the legal position in one line: you may only be in possession of the copyrighted BIOS if you are legally entitled to do so — in practice, you dumped it from a console you own.

Fix it in three steps

1. Have a BIOS file. If you don’t, that is the whole problem. Our legal BIOS guide explains how to dump firmware from your own PS1 (and why download sites are not a shortcut — their files can’t be verified, and the checksums advertised for them don’t match the genuine article).
2. Put it in the bios folder. Inside your ePSXe directory there is a bios folder; your .bin belongs there. (The folder ships with an erase.me placeholder — that’s normal.)
3. Select it. Config > BIOS, choose the file, save, and restart ePSXe. On Android: Preferences > BIOS, and make sure the file sits in a folder the app is allowed to see (scoped storage).

“It’s selected but the error stays”

• Wrong file: a 0-byte or misnamed dump, or a file that isn’t a BIOS at all. Re-dump or re-copy it.
• Region games vs BIOS region: some titles are picky; a BIOS from your own console of the same region as your discs is the cleanest pairing.
• HLE fallback confusion: ePSXe can attempt HLE BIOS emulation for some games (v2.0.18 improved HLE for specific titles), but HLE is partial — games that need a real BIOS will keep complaining or boot to the black screen.

Once the BIOS is selected properly, the warning disappears for good — it is a configuration state, not a recurring fault.

1. Is a BIOS selected?

No BIOS selected = black screen on most games. Open Config > BIOS (Windows) or Preferences > BIOS (Android) and confirm a .bin file dumped from your own console is chosen, then restart ePSXe. If you do not have one yet, our legal BIOS guide covers the only legitimate way to get one. Note that some titles boot on the HLE fallback and some simply refuse — a black screen with HLE selected is expected behaviour for those games.

2. Reset the video plugin to safe settings

An over-tuned or mismatched video plugin is cause number two. In Config > Video, open the plugin’s Configure panel and click Fast (the safe preset), then try the game. If it runs, re-apply your HD settings one at a time — the last one you changed was the culprit. Framebuffer effects set to disabled is a frequent offender: several games render their picture through them. Background in our OpenGL2 settings guide.

3. Check how you launched ePSXe

Running ePSXe.exe from inside the zip preview — or from a folder Windows protects, like Program Files — produces silent failures that look exactly like a black screen. Extract the full archive to its own folder and launch from there.

4. Test the disc image, not the emulator

• Load a different game image. If others run, this rip is the problem — re-rip the disc (see how to rip your own PS1 discs).
• A BIN without its CUE file, or a multi-track game ripped as a single track, commonly boots to black. Re-rip keeping the .cue alongside the .bin.
• If the image is still zipped or in an archive, extract it — ePSXe does not open games from inside zip files.

5. Android-specific checks

Grant the app access to the folder holding the game (scoped storage), confirm the BIOS path survived any app update, and switch the renderer to Software once: if the picture appears in software mode, the OpenGL renderer or a shader setting is at fault — the v2.0.19 shader changes make a shader reset worth trying. More Android context in the Android setup guide.

Still black after all five? Change nothing else and note which step changed the symptom — then see the troubleshooting index for the error-specific fixes.