A client caused an unhandled error while receiving or processing a packet. Disconnect
An error was detected which was caused by another client connected to you. The worst thing that can happen is that you’ll loose this one as a source.

Fatal error: unable to create socket on Port 4662
This error occurs if another application is using port 4662 to make connections. This is mostly the case when you use eMule at the same time as eDonkey without changing one of them to a different port.
It is not recommended to run both eMule and eDonkey or eMule and Overnet at the same time unless you have the (upload) bandwidth to do so.

ERROR: Your port 4662 is not reachable. You have a LOWID
eMule has detected that something is blocking your port 4662. This can be caused by firewalls or ill configured routers. Read the FAQ or search the forums on how to configure your firewall/router.

ERROR: Your port 4662 is not reachable. You have a LOWID http://www.edonkey2000.com/documentation/lowid.html ! Please correct your network config !
This error is similar to the one above. It will not pop up in the Log Window of the server but in the Serverinfo window. This message is generated by servers patched by Lugdunummaster. See here for details on Lugdunum patches.

Fatal Error while trying to connect. Internet connection might be down
The most obvious reason for this error is your connection is down, but it can also occur when your internet connection is very busy or you are using the firewall Zone Alarm which seems to handle many connections rather badly.

Error: Invalid part.met fileversion! (x.part.met => (null))
A serious error has occurred while eMule was writing data to a .part.met file. These are the files, in which eMule keeps track of temporary downloads.
The cause of this error is a crash of Windows or eMule. To recover the files you can try the following:

- Locate the file(s) in your Temp folder. If you cannot find them, you're out of luck
- Use a program like Known Metinator, DonkeyDoctor (Spanish, but program and help forum also in English) or eD2k RecoverMET to reconstruct the .met file.
- You can also try to run eDonkey with your current temp folder maybe it is able to correct the problem.
- See Troubleshooting -> Downloads for more details.

Always quit eMule before any operation and don't expect too much. This is a serious error and chances are good that you have to download the whole file again.

Status of a download shows "Erroneous"
This is also a file operation error. It can occur when:

- eMule is unable to open a .part file.
Check your Temp folder in Preferences for correctness
Check if any files in Temp folder are write protected
Restart eMule

- Completing a download or moving it to Incoming
Check your Incoming folder in Preferences for correctness
Check the available space on the hard disk of the Incoming folder
Restart eMule

If nothing helps, quit eMule, delete the preferences.ini and known.met in the folder you installed eMule to, and then restart.

Client 'xxx' (IP:xxx.xxx.xxx.xxx) caused an error: corrupted or invalid hashset received. Disconnecting client!
Nothing you can do on your side. This was caused by another client who sent you a invalid hashset upon a source request.

Error: Unable to hash downloaded part - hashset incomplete (XXX). This should never happen
This error is a bug which can occur with small files. They will nevertheless be completed correctly. You can safely ignore this one.

Unexpected file error while writing XXX : An unknown error occurred while accessing C:\Program Files\eMule\temp\YYY.part
While eMule was trying to complete a file, it encountered a problem with the part file. Possible reasons are

- a moved Temp dir or .part file
- another program is accessing this file (e.g. Virus scanner, another p2p)

Check the reasons and restart eMule.

Invalid versions tag in server.met (0x3C)
Loading or updating the server.met caused a problem. Either a invalid server.met was updated from an URL or the own server.met file has been corrupted. Try another URL for updating the server list or delete the server.met file if the error persists.

An attempt was made to access an unnamed file past its end
This message pop up is caused by invalid packets from servers or other clients. This message does not affect eMule's operation and is properly handled in the versions .28a+