为什么有些VBA错误不会触发错误处理？

Question

虽然今天早上更新了我的代码,但是我导致了一个错误 - 我用一个字符串替换了一个函数但忘记取出后面的括号,这导致代码无法运行.

但是,这并没有触发我的错误处理代码,因此它没有报告错误,并且通过单步执行代码花了我很长时间才找到它.

代码如下:

Private Sub Form_Close()

On Error GoTo ErrHandler

'Update to say the user is no longer logged in

        DoCmd.SetWarnings False
        DoCmd.OpenQuery "Last Logged Out"

'Backup data
If (strNameChecker <> "workshop.accdb") Then

        strBackupUser = Nz(GetFullName(), "default")
        strFriendlyNow = Replace(Now(), "/", "-")
        strFriendlyNow = Replace(strFriendlyNow, ":", "-")
        strNewFileName = "F:\Data\Central\Marketing\Databases\Prospects Database\Auto-Backups\TargetDBData - backed up by " & strBackupUser() & " on " & strFriendlyNow & ".mdb"
        BackupProspects "F:\Data\Central\Marketing\Databases\Prospects Database\TargetDBData.mdb", "" & strNewFileName & ""
        sSql = "INSERT INTO [Backup to Delete] ([Version Number]) SELECT '" & strNewFileName & "' AS Expr1;"
        DoCmd.RunSQL sSql


'Delete the temporary version of the front end.
        DoCmd.OpenQuery "Update - Version Shutdown"
        DoCmd.SetWarnings True
        Application.FollowHyperlink "F:\Data\Central\Marketing\Databases\Prospects Database\Prospects Database Shutdown.accdb"

End If

Exit Sub

ErrHandler:
DoCmd.SetWarnings True
MsgBox "The database has generated an error. Please contact the database administrator, quoting the following error message: '" & Err.Description & "'", vbCritical, "Database Error"

End Sub

错误是由strBackupUser在代码中途的两个括号引起的 - 删除这些并且代码工作正常 - 但为什么这个错误不会触发错误处理？

Answer 1

您似乎没有Option Explicit位于模块的顶部.因此,所有字符串变量都将以静默方式声明为Variant.我不确定编译器将对表达式做什么strBackupUser(),我猜它会尝试某种可怕的后期绑定对象或数组访问.

我建议Option Explicit先添加,然后显式声明所有变量为字符串,然后查看是否出现编译错误.

这是一个有用的"战争故事",说明了如何以及为何使用它.