<p>Click "Show scripts and coinbase" to see what that output really is. In this case it's <code>RETURN PUSHDATA(32)[8013...]</code></p>

<p><code>RETURN</code> (or <code>OP_RETURN</code>) causes the output to be unspendable.  The <code>PUSHDATA</code> then is just a way to insert the 32 bytes <code>8013...</code> into the blockchain.</p>

<p>The significance of that data is not necessarily known to anyone except the person who created the transaction.  But one possibility is that it's a hash of some other piece of data, which the creator wants to be able to prove was in existence on the date of the transaction.  This has a number of possible applications: the data could be an unpublished scientific discovery, or a nonce used in a provably fair random number scheme, or many other things.</p>

<p>See <a href="/questions/tagged/op-return" class="post-tag" title="show questions tagged &#39;op-return&#39;" rel="tag">op-return</a> for other questions about this.</p>

CC BY-SA 3.0
2017-12-09T15:31:04.007Z
Wow, [tag:op-return] is a complicated area, thanks for the link, I'll have to read up more.
Scott
CC BY-SA 3.0
2017-12-08T02:14:50.683Z
2017-12-08T02:14:50.683Z
Nate Eldredge
<p><code>Unable to decode output</code> is what Blockchain.info displays for any output that does not conform to a set of standard output script templates. Such outputs do not have associated addresses so there really isn't anything that a block explorer can show about them.</p>

<p>As stated by other answerers, the specific reason that this output could not be decoded is because it is an <code>OP_RETURN</code> output. There are many other things that could result in that message. Essentially any script that is not one of the standard templates will result in that message being shown.</p>

CC BY-SA 3.0
2017-12-09T15:17:20.763Z
Is there a list of standard templates or names for these templates?
Scott
CC BY-SA 3.0
2017-12-09T17:01:22.467Z
Some of the templates and all of the names can be found here: https://github.com/bitcoin/bitcoin/blob/master/src/script/standard.cpp#L21
Ava Chow
CC BY-SA 3.0
2017-12-08T07:58:20.743Z
2017-12-09T16:58:47.037Z
2017-12-09T16:58:47.037Z
Ava Chow
<p>It's possibly omni data, such as tether, which blockchain.info can't decode, see <a href="https://www.reddit.com/r/omni/comments/5zs411/i_cant_receive_btc_unable_to_decode_output_address/" rel="nofollow noreferrer">https://www.reddit.com/r/omni/comments/5zs411/i_cant_receive_btc_unable_to_decode_output_address/</a> - used for coins like tether, safex, etc.</p>

<p>It's like ERC20 tokens on ETH, but on the BTC blockchain instead - these coins, e.g. tether, don't have their own blockchain, instead they are sent as data in a btc transaction, where the small amount of BTC sent with it is used as miners fee. For omni coins, data encoded with Omni Protocol is stored in OP_RETURN field, to decode this data it needs to be viewed with a compatible block explorer, e.g. <a href="http://www.omniexplorer.info" rel="nofollow noreferrer">http://www.omniexplorer.info</a>, otherwise "Unable to decode output address" is displayed. </p>

CC BY-SA 3.0
2017-12-09T15:23:14.347Z
Are you saying that if I look up this address in particular on something like OmniExplorer that I should see some proof of it having Omni data associated with it?  Perhaps this proves this one isn't Omni data since nothing appears [here](https://omniexplorer.info/lookupadd.aspx?address=1NmiU6rTBhTojDjoMhUKshG2Dp4LF94e31).
Scott
CC BY-SA 3.0
2017-12-08T13:35:50.083Z
2017-12-08T13:35:50.083Z
philbob
<p>If you look at the output script for that output, you can see it looks like this:</p>

<pre><code> RETURN PUSHDATA(32) [some garbage]
</code></pre>

<p>This script, beginning with <code>OP_RETURN</code>, is called a null-data output, and is used to store arbitrary data in the blockchain. These outputs can never be spent, there is no way to make the script ever evaluate to true. Because of this, they will always show up as unspent on blockchain, and can be pruned from full node UTXO sets. </p>

<p>In general it's required that these outputs are accompanied by at least one 'normal' output. Any bitcoins in an OP_RETURN output are destroyed forever because they cannot be redeemed, that is why they all have 0 value</p>

CC BY-SA 3.0
2017-12-09T15:14:13.933Z
Are you saying bitcoins could be in an OP_RETURN but that it would be silly to do so since they can never be redeemed?  To be honest, I got lost when you said "can be pruned from full node UTXO sets".  Thanks for your answer.
Scott
CC BY-SA 3.0
2017-12-09T19:40:58.813Z
The UTXO set is the set of all unspent bitcoins in the whole blockchain. Full nodes use this set to check whether new transactions are spending valid outputs. These OP_RETURN outputs do not need to be stored there because they can never be spent
meshcollider
CC BY-SA 3.0
2017-12-08T03:36:40.680Z
2017-12-08T03:36:40.680Z
meshcollider
<p>On BlockChain.info, I have noticed a few transactions which send money to "Unable to decode output address".</p>

<p>For example, here is one:
<a href="https://blockchain.info/tx/624928439d2f668bab9f4cc1d9c4d2bc62a9603d8109d73d4fff8cf3043b68bd" rel="noreferrer">https://blockchain.info/tx/624928439d2f668bab9f4cc1d9c4d2bc62a9603d8109d73d4fff8cf3043b68bd</a></p>

<p>All of the ones that I have seen with this message have 0 Bitcoins associated with that transfer and then some other greater than zero amount of Bitcoins sent to a valid looking address.  These weird addresses also have their money marked as "unspent".  Do they ever get marked as "spent"?</p>

<p>What does this message mean and why are people sending Bitcoins this way?</p>

<blockchain.info><error>
What does "Unable to decode output address" mean?
Scott
# What does "Unable to decode output address" mean?

(Asked by: username_0 on 2017-12-08)

On BlockChain.info, I have noticed a few transactions which send money to "Unable to decode output address".

For example, here is one:
<https://blockchain.info/tx/624928439d2f668bab9f4cc1d9c4d2bc62a9603d8109d73d4fff8cf3043b68bd>

All of the ones that I have seen with this message have 0 Bitcoins associated with that transfer and then some other greater than zero amount of Bitcoins sent to a valid looking address. These weird addresses also have their money marked as "unspent". Do they ever get marked as "spent"?

What does this message mean and why are people sending Bitcoins this way?

**Tags:** blockchain.info, error


---

## 4 answers

### Answer by username_4 on 2017-12-08. Score: 9 | Accepted answer

If you look at the output script for that output, you can see it looks like this:
 RETURN PUSHDATA(32) [some garbage]

This script, beginning with OP_RETURN, is called a null-data output, and is used to store arbitrary data in the blockchain. These outputs can never be spent, there is no way to make the script ever evaluate to true. Because of this, they will always show up as unspent on blockchain, and can be pruned from full node UTXO sets. 
In general it's required that these outputs are accompanied by at least one 'normal' output. Any bitcoins in an OP_RETURN output are destroyed forever because they cannot be redeemed, that is why they all have 0 value

> **Comments:**
> **username_0**: Are you saying bitcoins could be in an OP_RETURN but that it would be silly to do so since they can never be redeemed?  To be honest, I got lost when you said "can be pruned from full node UTXO sets".  Thanks for your answer.  
> **username_4**: The UTXO set is the set of all unspent bitcoins in the whole blockchain. Full nodes use this set to check whether new transactions are spending valid outputs. These OP_RETURN outputs do not need to be stored there because they can never be spent  

---

### Answer by username_1 on 2017-12-08. Score: 7

Click "Show scripts and coinbase" to see what that output really is. In this case it's `RETURN PUSHDATA(32)[8013...]`

`RETURN` (or `OP_RETURN`) causes the output to be unspendable. The `PUSHDATA` then is just a way to insert the 32 bytes `8013...` into the blockchain.

The significance of that data is not necessarily known to anyone except the person who created the transaction. But one possibility is that it's a hash of some other piece of data, which the creator wants to be able to prove was in existence on the date of the transaction. This has a number of possible applications: the data could be an unpublished scientific discovery, or a nonce used in a provably fair random number scheme, or many other things.

See [op-return](/questions/tagged/op-return "show questions tagged 'op-return'") for other questions about this.

> **Comments:**
> **username_0**: Wow, [tag:op-return] is a complicated area, thanks for the link, I'll have to read up more.  

---

### Answer by username_2 on 2017-12-08. Score: 3

`Unable to decode output` is what Blockchain.info displays for any output that does not conform to a set of standard output script templates. Such outputs do not have associated addresses so there really isn't anything that a block explorer can show about them.

As stated by other answerers, the specific reason that this output could not be decoded is because it is an `OP_RETURN` output. There are many other things that could result in that message. Essentially any script that is not one of the standard templates will result in that message being shown.

> **Comments:**
> **username_0**: Is there a list of standard templates or names for these templates?  
> **username_2**: Some of the templates and all of the names can be found here: https://github.com/bitcoin/bitcoin/blob/master/src/script/standard.cpp#L21  

---

### Answer by username_3 on 2017-12-08. Score: 3

It's possibly omni data, such as tether, which blockchain.info can't decode, see <https://www.reddit.com/r/omni/comments/5zs411/i_cant_receive_btc_unable_to_decode_output_address/> - used for coins like tether, safex, etc.

It's like ERC20 tokens on ETH, but on the BTC blockchain instead - these coins, e.g. tether, don't have their own blockchain, instead they are sent as data in a btc transaction, where the small amount of BTC sent with it is used as miners fee. For omni coins, data encoded with Omni Protocol is stored in OP\_RETURN field, to decode this data it needs to be viewed with a compatible block explorer, e.g. <http://www.omniexplorer.info>, otherwise "Unable to decode output address" is displayed.

> **Comments:**
> **username_0**: Are you saying that if I look up this address in particular on something like OmniExplorer that I should see some proof of it having Omni data associated with it?  Perhaps this proves this one isn't Omni data since nothing appears [here](https://omniexplorer.info/lookupadd.aspx?address=1NmiU6rTBhTojDjoMhUKshG2Dp4LF94e31).  

---

