The knowledge base has no single article that says “do X” for every failed or stuck DSM update, but it does provide these safe recovery-related points:
- For a manual DSM update, Synology says to go to DSM > Control Panel > Update & Restore > DSM Update, click Manual DSM Update, Browse to upload the .pat file, then Update. The installation can take 20 to 40 minutes, and you should not shut down the system during the update. [11]
- If the update was offered for your model but you did not receive a notification, Synology notes that some models do not receive this update on the device and must use the Synology Download Center to download the patch manually. [2]
- Synology also says that after installing this update, you will not be able to downgrade to a previous DSM version. [2], [11]
- If the system partition has degraded or crashed, Synology’s recovery path is to back up your data, then use Mode 2 to reset the NAS and reinstall DSM. For DSM 6.2.4 or above, Synology points to the DSM 7 reset article; for DSM 6.2.3 or earlier, use the older reset article. [12]
- If you end up in a reinstall situation with drives still inside the NAS, one community forum solution says to use the rear RESET hole, then choose Reinstall in Web Assistant and do not select wipe/format; that was described as wiping only the system partition. This is forum advice, not an official Synology procedure, so use caution. [9]
- If the NAS no longer starts or is inaccessible and you need data recovery, Synology advises checking whether the storage pool has data protection first; for protected RAID types, and for unprotected ones with no free slot, recovery may require a PC. [8]
What the knowledge base does not provide here is a single guaranteed safe step-by-step rescue flow for every “update failed / stuck” case. The safest documented path is:
1. wait long enough for the update to finish if it is still in progress,
2. use the official manual DSM update path,
3. if the system partition is damaged, follow Synology’s Mode 2 reset / reinstall guidance after backing up data. [11], [12]
Sources used: [11], [2], [12], [9], [8]