Assuming you have installed PJ64 from the official installer (so the plugins are not missing) this error generally indicates that default plugin has not started, i.e. it is invalid for your system. To resolve this, please read system requirements then video initialisation troubleshooting.

(this error msg exists with variations for each type of plugin)

This indicates a problem with your Windows installation. read this Microsoft support page or search their site for more information.

"...make sure you have a properly configured 3d graphics card compatible with Direct3D8" (or similar msg).

Please read Manual and Guides > Troublshooting >  Video Initialisation (Initialization) problems for a full explanation of how to solve this problem (it's a long topic).

 

Please see troubleshooting category for full details for this problem as it's a complex topic.

This text (or a translation of it if using Lang file) is shown in the "Good Name" field (by default the first column of the ROM Browser) if the ROM is not in the RDB.

1. Right click on the game, click 'ROM information' (or 'Properties'), and read the filename to work out which ROM it is refering to on your system.
2. You must then verify your ROMs with GoodN64.
3. Also look for an updated RDB (download section)!

Non-[!] ROMs are not officially supported by PJ64. (People with a reason to use other kinds of ROM will be able to add them themselves to the RDB).

1. Usually indicates a Bad ROM - read how to verify your ROMs.
2. If your ROMs are [!], this error may indicate incorrect ROM Settings. Check download section for updated RDB.
3. If none of the above help, try restarting the emulator and don't load from a state save (loading from native saves is OK). This will test for random memory/core errors.
   

1. Read ROM Browser notes to check game is supported
2. Check Games section! for known issues for the game.
3. Check download section for updated RDB.
   

 

Try updating your DirectX version and controller drivers, if there are any.

Update your DirectX version to at least 8.

You have selected a zip file without a valid N64 ROM inside, or one that the emulator can find.

Check the file contains a valid N64 ROM which can be extracted by a zip program. Try recompressing the ROM using a reliable zip utility.

1. Usually indicates a Bad ROM - read how to verify your ROMs.
2. If your ROMs are [!], this error may indicate incorrect ROM Settings. Check download section for updated RDB.
3. Cheat codes can cause core errors. Disable all cheat codes and reset the game (default shortcut: F1). Load from the native save (through the game's menus). Do not load from a state save (F7 etc.), because states store memory changes. Usually loading from the native save is OK. In some cases cheat codes can damage the native save aswell so that the game crashes; it may even be necessary to start the game again, either by using a different "slot" or by deleting the native date in your Project64 \Save subfolder. (try all other suggestions here first!).
   
4. If none of the above apply, try restarting the emulator and load from the native save - through the game's menus (do not load any PJ64 state save (F7 etc.) because state saves can store memory errors). This point will test for other random memory/core errors. If you find this works, overwrite your bad state save with a new clean state save.
   

1. Check (with a Task Manager) you have no zombie (processes without windows) instances of PJ64 running. If you don't understand this, try logging off and back on windows or restarting your PC.
2. Check that your save files are not read-only.
   
3. Check that you have write permissions (i.e. NTFS permissions in WinXP) to the save directory, or move your save dir to somewhere you have write access such as your windows user profile folder.
4. Read the notes about Multiple Instances in the Manual.

Nearly always indicates a bad ROM - read how to verify your ROMs. Only [!] ROMs are supported by Project64.

1. This nearly always indicates you have a bad ROM - read how to Verify ROMs. 
2. In rare cases, this could indicate incorrect ROM Settings, so check you have the latest RDB (Downloads > Updates) and haven't changed any settings.  

The only compressed standard supported is .zip. if your file is compressed with anything else (.rar, .7z, .ace etc etc.), decompress it with the appropriate program then try loading. If it still doesn't work, verify the uncompressed file with GoodN64 (see elsewhere in documentation).

This error should rarely appear in PJ64 v1.6 since the resource usage was made lower, so  if you're using an older version please upgrade to v1.6 or later
If you still see the error, we suggest you try the following in this order. Try running Project64 after each step:

1. Free as much RAM as possible (preferably over 100MB) by shutting down unneeded processes.
2. Make sure you have set a large permanent Windows swapfile (preferably over 512MB).
3. If you use WindowsXP try using a Windows compatibility mode (right click on Project64.exe > Properties > Compatibility. Choose e.g. Windows 98, and press OK). Or if you are using a compatibilty mode, try not using one, or using a different one.
4. You could try running a "RAM freeing/compacting" type program for example FreeRAM XP Pro (this is not an endorsement of this particular software).
   
5. Try removing any spyware on your computer with a spyware removal pograms sych as Ad-Aware or Spybot.
6. Some users report that Windows XP Hotfix - KB828741 or KB841356 causes this error, you could try uninstalling that (though we are not responsible for any security implications of doing this!). Others say installing SP2 for WinXP fixed this problem.
7. If you use a program called MSN Plus! or Messenger Plus try closing them. Also other IM programs.
8. Some users report uninstalling Logitch Mouseware fixed this problem.
9. If you use a Win9x based OS (Win98,WinME) some users suggest you should probably upgrade to WinXP.

This is a rather mysterious problem rarely seen by the PJ64 team...

Close the ROM ("End Emulation") or simply quit PJ64 with the GUI or ALT+F4

Probably because the graphics plugin is asking your video card to do something it is not capable of. Read the log (open in text editor) and it should provide some clues to where the problem is. Check you have everything set up right in the plugin and your drivers. Ultimately you may need to get a better graphics card to avoid the errors... you cannot stop the plugins from logging, you could try making the files read only. The occasional error from even a good graphics card is normal and not a cause for concern unless you notice any ill effects.