# Start9 Electrs Startup Failure After StartOS Upgrade

\*\*Date:\*\* 25 July 2026

\## Summary

After upgrading StartOS, the \*\*Electrs\*\* service failed to start on \*\*both\*\* Start9 servers.

The issue was \*\*not\*\* related to the Bitcoin blockchain, Electrs index, SSD, hardware or network. The root cause was a configuration conflict introduced during the migration process.

\---

\# Affected Systems

\## Server 1

\- Hardware: AMD Ryzen 7 5825U  
\- Bitcoin implementation: Bitcoin Knots  
\- Electrs version: 0.11.1

\## Server 2

\- Hardware: Intel Celeron N4505  
\- Bitcoin implementation: Bitcoin Core  
\- Electrs version: 0.11.1

Both systems exhibited the identical failure immediately after the StartOS upgrade.

\---

\# Symptoms

Electrs repeatedly exited during startup.

The log reported:

```  
Error: ambiguous configuration - auth and cookie\_file can't be specified at the same time  
```

\---

\# Investigation

The Electrs configuration file was located at:

```  
/media/startos/data/package-data/volumes/electrs/data/main/electrs.toml  
```

Its contents were:

```toml  
cookie\_file = "/mnt/bitcoind/.cookie"  
daemon\_rpc\_addr = "10.0.3.1:63174"  
daemon\_p2p\_addr = "10.0.3.1:58334"  
network = "bitcoin"  
electrum\_rpc\_addr = "0.0.0.0:50001"  
log\_filters = "INFO"  
auth = "bitcoin:xxxxxxxxxxxxxxxx"  
```

Electrs accepts \*\*either\*\*

\- cookie authentication

or

\- username/password authentication

but \*\*not both simultaneously\*\*.

The migration left both options in the configuration.

\---

\# Resolution

Create a backup:

```bash  
sudo cp \\  
/media/startos/data/package-data/volumes/electrs/data/main/electrs.toml \\  
/media/startos/data/package-data/volumes/electrs/data/main/electrs.toml.backup  
```

Remove only the `auth` line:

```bash  
sudo sed -i '/^auth = /d' \\  
/media/startos/data/package-data/volumes/electrs/data/main/electrs.toml  
```

Verify:

```bash  
sudo nl -ba \\  
/media/startos/data/package-data/volumes/electrs/data/main/electrs.toml  
```

Correct result:

```toml  
cookie\_file = "/mnt/bitcoind/.cookie"  
daemon\_rpc\_addr = "10.0.3.1:63174"  
daemon\_p2p\_addr = "10.0.3.1:58334"  
network = "bitcoin"  
electrum\_rpc\_addr = "0.0.0.0:50001"  
log\_filters = "INFO"  
```

Restart the Electrs service from the StartOS interface.

Electrs started immediately without rebuilding the index.

\---

\# Root Cause

A StartOS migration bug appears to leave the legacy

```toml  
auth = "bitcoin:..."  
```

entry in `electrs.toml` while simultaneously enabling

```toml  
cookie\_file = "/mnt/bitcoind/.cookie"  
```

This produces an invalid Electrs configuration.

\---

\# Evidence

\- Reproduced on \*\*two independent Start9 servers\*\*  
\- Different hardware platforms  
\- Different Bitcoin implementations (Core and Knots)  
\- Identical configuration conflict  
\- Identical error message  
\- Identical fix

This strongly indicates a migration bug rather than a hardware or installation issue.

\---

\# Lessons Learned

\- Do \*\*not\*\* delete the Electrs database.  
\- Do \*\*not\*\* resync Bitcoin.  
\- Do \*\*not\*\* rebuild the Electrs index.

Always inspect:

```  
/media/startos/data/package-data/volumes/electrs/data/main/electrs.toml  
```

If both `cookie\_file` and `auth` are present, remove only the `auth` entry.

\---

\# Recommendation

Report the issue to the Start9 developers with:

\- StartOS version  
\- Electrs version  
\- Exact error message  
\- Original `electrs.toml`  
\- Corrected `electrs.toml`  
\- Confirmation that the issue occurred on two separate servers and was resolved by removing the `auth` line.