Share your experience!
I have just brought a xperia M4 Aqua and have been trying to register it on the sony site yet everytime i put my IMEI number in it keeps saying The IMEI is not valid ye the number starts with 35 and is 15 numbers long getting frustrating as i have tried for hours and tried everything i can think of.
Sorry to hear that you have issues registering your phone.
Did you manage to solve the issue? From what i can see here you have a M4 Aqua with a proper IMEI registered in your account.
EDIT:
@Hampus just mentioned that you sent him a PM as well with your IMEI so it was he who added it. You should see it in your account now. Please let us know if you still don't see it.
Hey! 
Were you able to finally solve the issue?
I am having the same problem when I tried to register my Sony Xperia M4 Aqua to mysupport page. An error message says "IMEI not valid'.
I tried doing it again and again, entering one number at a time and counting if it's 15 digits but I still get the same error message all the time.
What should I do with it?
Even I'm facing the same issue. I've M4 Aqua Dual and it is not accepting the IMEI1 and IMEI2 also.
Hi everybody. I'm Saulo from Mexico.
I recently (5 days ago) bought an Xperia m4 Aqua, which is an awesome phone but last night someone stole it and now I'm trying to find it registering my phone by IMEI but I'm not able to register it on the section "add a device" in " my support". Even thought I write my correct IMEI it still saying that it is incorrect. May someone help me, please? 
I have a same problem with this in my M4 Aqua. How to fix this?