Powershell: Backup-Sqldatabase fails to resolve path

try some thing like this:

Function Invoke-SQLBackup {[CmdletBinding()]param(    [Parameter(Mandatory=$true)]    [String] $ServerInstance,    [Parameter(Mandatory=$true)]    [String] $DatabaseName,    [Parameter(Mandatory=$true)]    [String] $BackupFile    )if (Get-Module -ListAvailable -Name SQLPS)    {        Import-Module SQLPS -Force            Backup-SqlDatabase -ServerInstance $ServerInstance -Database $DatabaseName -BackupFile $BackupFile -Verbose     }ELSE    {        Write-Output "SQLPS Module not Installed. Please install and try again."    }}

I wrote and executed the above in my test environment and the backup completed without issue.

Syntax to run and output would look similar to the below:

PS SQLSERVER:\> Invoke-SQLBackup -ServerInstance 'SERVERNAME\INSTANCENAME' -DatabaseName 'TestDatabase' -BackupFile 'C:\SomePath\Filename.bak'    WARNING: The names of some imported commands from the module 'SQLPS' include unapproved verbs that might make them less discoverable. To find the commands with unapproved verbs, run the Import-Module command again with the Verbose parameter. For a list of approved verbs, type Get-Verb.    VERBOSE: Performing the operation "Backup-SqlDatabase" on target "[SERVERNAME\INSTANCENAME]".    VERBOSE: BACKUP DATABASE [KB] TO  DISK = N'C:\SomePath\FileName.bak' WITH NOFORMAT, NOINIT, NOSKIP, REWIND, NOUNLOAD,  STATS = 10    VERBOSE: 10 percent processed.    VERBOSE: 21 percent processed.    VERBOSE: 32 percent processed.    VERBOSE: 40 percent processed.    VERBOSE: 51 percent processed.    VERBOSE: 61 percent processed.    VERBOSE: 72 percent processed.    VERBOSE: 80 percent processed.    VERBOSE: 91 percent processed.    VERBOSE: Processed 296 pages for database 'DatabaseTest', file 'DatabaseTest' on file 4.    VERBOSE: 100 percent processed.    VERBOSE: Processed 2 pages for database 'DatabaseTest', file 'DatabaseTest_log' on file 4.    VERBOSE: BACKUP DATABASE successfully processed 298 pages in 0.217 seconds (10.728 MB/sec).

Since you are trying to save to default sql folder in program files make sure you are running the script as an account that has access to write to the location. For example an administrator account or if you have a service account for backups either of those would works. Administrator account should have access by default to the program files folder assuming permissions were not changed.

Hope this helps.