There have been reports of issues when using Paymetheus 0.5.0 after upgrading from an older release. This post describes the issue and a workaround. When an updated 0.5.0 Paymetheus is first run, and the new dcrd begins resyncing the blockchain using its new database, the wallet will immediately mark itself out of sync. This prevents all usage of the wallet until it is back in sync. Unfortunately, Paymetheus does not handle this situation well and will throw up a cryptic error dialog at startup. This occurs because when the wallet, which was previously in sync with a dcrd on the old database, suddenly connected to the new dcrd version and discovered it was missing most of the blockchain. At this point the wallet marks itself out of sync, internally performs a giant reorganize to remove all blocks that the new dcrd hasn't processed yet, and begins to rescan to catch up to the new dcrd. While in this state, the wallet is essentially unusable and Paymetheus is not able to perform its normal startup routine. The workaround is to leave Paymetheus running with this error dialog being shown. While opened, both wallet and dcrd will continue to update in the background. Once dcrwallet has finished its rescan, Paymetheus will be reusable again on next startup. It is important to leave the error dialog open, as closing it will cause both Paymetheus and dcrwallet to exit. Unfortunately there is no indication of when the rescan finishes, so you will just need to leave the error dialog open for a few hours and hope for the best. One possible way to determine whether this resync is finished is to watch the CPU usage of both dcrd and dcrwallet in Task Manager. When each of these processes drop to nearly 0% CPU, the resync is likely done. Fortunately, closing the error dialog and stopping the sync when it is not complete does not reset all progress. On next startup the issue will still remain, but the resync will begin where it left off. Keep it running until it is complete, and then after closing the error dialog and opening Paymetheus again, the wallet should be usable.