add notes for resolving hdd error if encountered

doc/update0716.md

@@ -25,6 +25,27 @@ cd ~/notary_docker_3p
 ./start
 ```
 
+**NOTE:** If your blockchain data folder contains data from an older daemon version (before we switched to the 0.7.x versioning, such as 3.x.x), you might encounter this error when starting the 0.9.0 daemon:
+
+```bash
+2024-08-21 18:49:12 ERROR: LoadBlockIndex() : failed to read value
+2024-08-21 18:49:12 : Error loading block database.
+error in HDD data, might just need to update to latest, if that doesn't work, then you need to resync.
+```
+
+__This should only be an issue on verteran nodes that have been running for a long time without a recent "sync from scratch"__. 
+
+In this case, you have several options:
+
+- Resync from scratch (slowest but most accurate, allowing your node to recalculate value pools).
+- Bootstrap from [dexstats.info](https://dexstats.info/bootstrap.php) (fastest, but since the initial sync version is unknown, value pools might be incorrectly calculated). Value pools refer to the stats for transparent, sprout, sapling, and burned chain values.
+- Reindex with `-reindex` (but options `resync` and `bootstrap` are recommended).
+
+@decker has provided a [script](https://raw.githubusercontent.com/DeckerSU/komodo_scripts/master/restart_kmd_daemons.sh) to simplify the upgrade process. Just run it on a host with launched Komodo daemons within a directory containing the new version of komodod and komodo-cli, and all launched instances will be stopped and re-launched with the new version of the daemon. Very convenient!
+
+__This script is not compatible with the docker container setup on 3P, but these were likely sync'd from scratch recently enough to not encounter this error__
+
+
 
 ### Update `mm2` to the latest version.