New Telly HDMI Problem

[Doofus]

New LG tv, replacing another LG.

Whenever I switch it on, I get a message telling me the programme cannot be watched via HDMI because of an HDCP error. It clears after a few seconds, which I understand is some kind of handshake thing between the tv and my Humax Aura.

Is it just a case of getting a new HDMI cable? It worked fine on the old telly.

[jurbie]

My LG, which is a few years old, also does this but not every time so maybe an LG quirk. Sorry, can't help beyond that but interested if there is a solution.

[Doofus]

It turns out it does it with the PS5 as well, so that suggests it's less likely to be the cable.

[butchstewie]

This is lifted straight from Claude so pinch of salt and all that.

Short version: that message is the HDCP handshake (the copy‑protection negotiation over HDMI) failing to complete instantly when the TV powers up, then succeeding a moment later. It's a link that has to be renegotiated every time the HDMI connection comes back to life. The fact that it happens with *both* the Aura and the PS5 tells you it almost certainly isn't either of those boxes — it's the TV, the ports, or the cables in between.

Since it's a new TV, the variable that's changed is the set itself, and a new LG is usually more demanding on bandwidth than the one it replaced. Things to try, roughly in order of how often they fix it:

• The cables first.** If you carried the old HDMI cables over, that's my main suspect. A handshake that fails then recovers is the classic symptom of a cable that's marginal for the bandwidth being asked of it. A new 4K LG running HDCP 2.2/2.3 wants genuine "Premium High Speed" or "Ultra High Speed" cables; older or cheaper leads will often pass a picture but stumble on the handshake. Swap the leads for the Aura and the PS5 and see if it clears.

• The Deep Color setting.** On the LG, go to Settings → (General →) External Devices → **HDMI Ultra HD Deep Color**, and check the setting for the ports the Aura and PS5 are plugged into. Try toggling it. Turning it *on* enables full 4K bandwidth but is fussier about cables; turning it *off* drops the link to a less demanding mode that handshakes more reliably (at the cost of 4K/HDR on that port). Worth testing both ways to see which is the trigger.

• SIMPLINK (HDMI‑CEC).** Settings → General → **SIMPLINK (HDMI‑CEC)**. CEC lets the devices wake the TV and vice versa, and the power‑on sequencing can race the HDCP handshake. Try turning it off and see if the message stops.

• Quick Start+.** If you have this enabled (Settings → General → Devices/Power), try turning it off — its fast‑boot standby state can sometimes affect how cleanly HDMI comes up.

• A clean handshake.** Power everything fully off at the mains — TV, Aura and PS5 — for a minute, then power back up. This clears any stale HDCP state held in memory.

• Firmware.** Make sure the TV is on the latest webOS update, and that the Aura and PS5 are current too.

Menu names vary a little by webOS version, but those paths are close. If swapping the cables alone kills it, you've found it — that's the most common culprit by a wide margin for a handshake that fails and then recovers.

Is the message new behaviour that the old TV never showed, and are you reusing the previous cables? That'll narrow it down quickly.

[Doofus]

Thank you. I'll have a play.

[Sporky]

Almost every AV issue is cable-related.

You don't need to spend silly money on a cable. The Amazon Basics ones are specification-compliant.

Don't get a longer cable than you need.

[Dave Hedgehog]

ugreen make decent braided and certified HDMI 2.1 cables for a sensible price, never had a problem with them or their display port cables

https://www.amazon.co.uk/UGREEN-Certified-Compatib...

[butchstewie]

Totally.

There's no need to pay a fortune for cables but having spent all that money I think it warrants cables that are certified as meeting the technical spec.

[Digger]

Dave Hedgehog said:

ugreen make decent braided and certified HDMI 2.1 cables for a sensible price, never had a problem with them or their display port cables

https://www.amazon.co.uk/UGREEN-Certified-Compatib...

Yeah that's a good cable.

I went with the Snowkids cable as a I liked the name & it was a tad cheaper

https://www.amazon.co.uk/dp/B08BC36QNY


ETA - May as well get a 2.2 standard for future-proofing?

https://www.amazon.co.uk/UGREEN-Ultra96-Certified-...

Edited by Digger on Sunday 28th June 15:58

[Dave Hedgehog]

Digger said:

Yeah that's a good cable.

I went with the Snowkids cable as a I liked the name & it was a tad cheaper

https://www.amazon.co.uk/dp/B08BC36QNY

i went with ugreen because they make a wide range of high quality electronics and not the usually rebadged aliexpress tat, their nexode power banks are excellent

https://uk.ugreen.com/

[Digger]

Dave Hedgehog said:

Digger said:

Yeah that's a good cable.

I went with the Snowkids cable as a I liked the name & it was a tad cheaper

https://www.amazon.co.uk/dp/B08BC36QNY

i went with ugreen because they make a wide range of high quality electronics and not the usually rebadged aliexpress tat, their nexode power banks are excellent

https://uk.ugreen.com/

Just did a search of all my Amazon purchases & it is currently 7 vs 4 in favour of uGreen

[Doofus]

It just seems odd that on Thursday both HDMI cables were fine and now, with the new tv, they're not.

[Sporky]

Doofus said:

It just seems odd that on Thursday both HDMI cables were fine and now, with the new tv, they're not.

Does the new telly box support a higher refresh rate, or HDR, or anything else that the old one didn't?

It might be that the sources and TV support standards that need higher bandwidth than your cables can reliably carry. HDCP itself isn't high bandwidth at all, but it's very often the first thing to go when you push a cable too far.

[Doofus]

Sporky said:

Doofus said:

It just seems odd that on Thursday both HDMI cables were fine and now, with the new tv, they're not.

Does the new telly box support a higher refresh rate, or HDR, or anything else that the old one didn't?

Probably; the other one was about six years old.

[Dave Hedgehog]

make sure to update the firmware on the LG

[Sporky]

Doofus said:

Probably; the other one was about six years old.

For the cost of a couple of decent enough cables I think it's worth trying.

[Doofus]

Sporky said:

Doofus said:

Probably; the other one was about six years old.

For the cost of a couple of decent enough cables I think it's worth trying.

But I bought new cables six years ago, dammit!

[Digger]

Which LG telly did you buy Doofus?

[Doofus]

An OLED C55 HDR something or other.

[Beetnik]

Be sure to update your firmware:

https://gscs-b2c.lge.com/open/downloadFile?fileId=...

https://www.lg.com/uk/support/product-support/