Safe guard mode, E04

Disconnect the battery pack or the DC power plug on the back of the camcorder if the LCD screen displays error code "01," "02" or "06." This resets the camcorder and unlocks the unit from safe mode. Wait 10 minutes before reconnecting power.

My JVC Camcorder Is Stuck in Safe Mode - eHow UK

How to Get a JVC Camcorder out of Safeguard Mode

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These cameras contain sensors that can detect issues in their operation. When they detect an issue, they can put the camera into a special "Safeguard Mode" that ...

E04
remove and reattach battery,
Unit in safeguard mode.

Following are the solutions:<br /> 1. Through your camera in dustbin;<br /> 2. crush it with hammer <br /> 3. Put it on fire

Here is some information regarding the E04 error message from http://www.techlore.com/article/10974/JVC-Camcorder-Stuck-in-Safe-Mode/:

"JVC notes that you are also given a malfunction code when the unit is placed into safeguard. If it displays code 01, 02, or 06 you should remove
the battery and powersupply and wait for a while. Code 03 and 04 indicate that you should eject and reinsert the tape.

If neither of these solutions work, your only alternative is to bring it to a shop or send it to JVC for diagnosis or repair. Unfortunately, there is no other way to clear the condition."

This doesn't seem uncommon, and indicates a bad tape is loaded, or unfortunately, that the camcorder requires servicing.

According to http://www.techlore.com/article/10974/JVC-Camcorder-Stuck-in-Safe-Mode/,

"JVC notes that you are also given a malfunction code when the unit is placed into safeguard. If it displays code 01, 02, or 06 you should remove
the battery and powersupply and wait for a while. Code 03 and 04 indicate that you should eject and reinsert the tape.

If neither of these solutions work, your only alternative is to bring it to a shop or send it to JVC for diagnosis or repair. Unfortunately, there is no other way to clear the condition."

If you are getting E03 or E04 errors on every tape you try, it sounds like a servicing is required.

An excerpt from http://www.techlore.com/article/10974/JVC-Camcorder-Stuck-in-Safe-Mode/:

"JVC notes that you are also given a malfunction code when the unit is placed into safeguard. If it displays code 01, 02, or 06 you should remove
the battery and powersupply and wait for a while. Code 03 and 04 indicate that you should eject and reinsert the tape.

If neither of these solutions work, your only alternative is to bring it to a shop or send it to JVC for diagnosis or repair. Unfortunately, there is no other way to clear the condition."

According to this, E04 denotes a problem with the recording media or the mechanical bits that deal with the tape. Hopefully trying another tape helps.

I tried every method I could find from people posting on the web, but the method that worked for me is this.

1. Eject the tape and close the tape holder.
2. Turn the camera off and remove the battery.
3. Put the battery back in. Leave the camera off.
4. Open the tape holder.
5. Slide the tape in, but as you press the holder in to accept the tape, keep your finger pressing in on the holder, being careful not to slow the tape holder from moving downward.
6. Turn the camera on.
7. If it doesn't work the first time, press more firmly to help the tape holder accept the tape.

That's it. This method seems to work for me and lets me use the camera for a long while. If the camera is sitting unused for more than a few hours, I have to do it again. And each time I insert a tape, I make sure that I keep pressing as the tape holder lowers the tape.

The mechanism is out of sync, put a tape in and hold it, it wont go in but will try to open don't let it, remove the battery and reattach, let the tape eject, rinse and repeat 3 or 4 times and it will finally accept the tape.

Here's what i found. I was able to clear the message by opening and closing and ejecting the cassette. I also had to play with the battery at the same time. Keeping the cassette door open and then pulling out the battery. After is did this a couple of times i got the message to clear. I too haven't used my camcorder for some time and now that the error message has cleared the camcorder tells me that i need to clean the heads. Hope this helps. Below is the message i found that pointed me toward ejecting the cassette. An error indication (E03 or E04) appears. - (E03 or E04 UNIT IN SAFEGUARD MODE REMOVE AND REATTACH BATTERY) This massage a malfunction of some kind has occurred. In this case the camcorder's functions become unusable. - Eject the cassette once and re-insert it, then check if the indication clears. When it does, you can resume using the camcorder. If the indication remains, consult your nearest JVC dealer or service center

You mix te info with Write protected tapes.
Safe guard mode is caused by the motor that takes the tape out of it's case, through the mechanics and past the video head.
If for some reason the electronics detect that it's been done by too much force, the safe guard issue promts.