# Known Issues
Details on previously identified known issues are provided below. Details on known issues identfied
in the current release are provided in the [Changelog ](CHANGELOG.md ).
Known issues are open issues categorized as [Very High or High impact ](https://wiki.hyperledger.org/display/BESU/Defect+Prioritisation+Policy ).
## Intrinsic gas exceeds gas limit
Calling delete and set to 0 Solidity mapping in Solidity [fails with an intrinsic gas exceeds gas limit error. ](https://github.com/hyperledger/besu/issues/696 )
## Eth/65 not backwards compatible
From v1.4.4, `eth/65` is [disabled by default ](https://github.com/hyperledger/besu/pull/741 ).
The `eth/65` change is not [backwards compatible ](https://github.com/hyperledger/besu/issues/723 ).
This has the following impact:
* In a private network, nodes using the 1.4.3 client cannot interact with nodes using 1.4.2 or earlier
clients.
* On mainnet, synchronizing eventually stalls.
A fix for this issue is being actively worked on.
## Fast sync when running Besu on cloud providers
A known [RocksDB issue ](https://github.com/facebook/rocksdb/issues/6435 ) causes fast sync to fail
when running Besu on certain cloud providers. The following error is displayed repeatedly:
```
...
EthScheduler-Services-1 (importBlock) | ERROR | PipelineChainDownloader | Chain download failed. Restarting after short delay.
java.util.concurrent.CompletionException: org.hyperledger.besu.plugin.services.exception.StorageException: org.rocksdb.RocksDBException: block checksum mismatch:
....
```
This behaviour has been seen on AWS and Digital Ocean.
Workaround -> On AWS, a full restart of the AWS VM is required to restart the fast sync.
Fast sync is not currently supported on Digital Ocean. We are investigating options to
[add support for fast sync on Digital Ocean ](https://github.com/hyperledger/besu/issues/591 ).
## Bootnodes must be validators when using onchain permissioning
- Onchain permissioning nodes can't peer when using a non-validator bootnode [\#528 ](https://github.com/hyperledger/besu/issues/528 )
Workaround -> When using onchain permissioning, ensure bootnodes are also validators.
## Privacy users with private transactions created using v1.3.4 or earlier
A critical issue for privacy users with private transactions created using Hyperledger Besu v1.3.4
or earlier has been identified. If you have a network with private transaction created using v1.3.4
or earlier, please read the following and take the appropriate steps:
https://wiki.hyperledger.org/display/BESU/Critical+Issue+for+Privacy+Users
