Sage 50 Canada: This database may be damaged, or it is not a valid Simply Accounting
Sage 50 could not open the file: usually a stale lock from another session, sometimes a wrong or incomplete file, sometimes real damage.
If Sage 50 Canada, the product long sold as Simply Accounting, shows you the message “This database may be damaged, or it is not a valid Simply Accounting database, or it is being used by other users.” it means the program tried to open the file and could not get exclusive access to a database it could read. The three causes are listed in roughly the reverse of the order you should worry about them. Most of the time the real reason is the last one: the file is simply open somewhere else, and that one is harmless.
Rule out the harmless cause first: someone else has it open
The database can only be opened by one session at a time. If a colleague has the company open on another workstation, or a previous session crashed without releasing its lock, you will see this exact wording even though the file is perfectly fine.
Close the program on every computer that can reach the data over the network, confirm no one else is in it, restart the machine that crashed or lost power, and try again. Resist the urge to delete whatever files sit next to the database in its folder; a stale lock usually clears once every copy of the program is closed, and deleting the wrong thing can turn a locked file into a damaged one.
Check that you are opening the right file
“Not a valid Simply Accounting database” often has a boring explanation: the file you pointed the program at is not a complete database at all. Typical culprits are a copy made while the database was in use, a copy that was interrupted partway through, a file that was renamed, or a backup that was opened directly instead of being restored through the program. If the data was recently moved or copied, go back to the original location or the original backup and open that instead.
If it really is damaged
Damage usually has a story behind it: a power failure or forced shutdown while the database was writing, a network drop in the middle of a save, a failing drive, or security software that quarantined part of the data. The tell is that the message repeats with every user logged out, on every machine, after a restart.
At that point, stop retrying. Repeated attempts against a failing drive can make recovery harder, and you should never overwrite your most recent good backup with a broken file. If an older backup opens, use it and re-enter the gap. If the only copy throws this message, the database needs professional attention, and we would rather say so plainly than have you lose a weekend to it. Our engineers repair damaged Simply Accounting and Sage 50 Canada databases, and every job starts with a free evaluation of the file.
If you were planning a move to QuickBooks
A database in this state will not convert cleanly through the usual import routes, but the data is often still reachable. We can frequently recover it from the damaged database and deliver it straight into QuickBooks, so the repair and the conversion happen as one step rather than two. See Simply Accounting to QuickBooks conversion for how that works.
The next step we recommend
Before you spend an evening on this, get a free evaluation. Send us the file, or the smallest copy that shows the message, and we will tell you what is actually wrong with it and whether the data is recoverable. You will at least know where you stand.