Here is a simple guide on how to fix DMM error 7206 or 3103. hope these methods will work for you.
DMM Error 7026
“The game is already running,” could be true or not. Though, to resolve this, is reportedly to include the game or the DMM Games Player into your Antivirus’ exception list. Please refer to your Antivirus how to do this. Failing that (although not recommended since you’ll lose protection against vulnerabilities), temporarily disable your antivirus.
DMM Error 3103
There is an invalid character in either the email or password you are using – keep in mind, passwords can only contain alphanumeric characters (letters and numbers) and not symbols
Credit to Google Doc
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