About the Bug in VBScript.RegExp

[hanamichi77777]

In the Office update (ver.2508) at the end of August, there has been an example of a code using VBScript.RegExp.Replace suddenly encountering an error.
Please be careful.
https://nolongerset.com/bug-assertion-failed-regexp/

[hanamichi77777]

Conditions for the occurrence of a VBScript.RegExp.Replace bug
1 Office ver.2508
2 CreateObject("VBScript.RegExp")
3 The second argument of Replace must be a variable

Sub Bug()
  Dim re As Object: Set re = CreateObject("VBScript.RegExp")
  re.Pattern = "\D"
  Dim str As String: str = ""
  Debug.Print re.Replace("Abc123", str)   'Bug
 'Debug.Print re.Replace("Abc123", (str)) 'BugFix
End Sub

The SelenumVBA program is referenced by "Dim oRegExp As New VBScript_RegExp_55.RegExp"
and does not use "CreateObject("VBScript.RegExp")", so I don't think there will be any errors

[hanamichi77777]

It's added
It was reported that errors occur when using Lookahead (?=) or NegativeLookahead (?!) in VBScript.Regexp, and it has certainly been reproduced.
This error is troublesome and can occur even when setting the reference.
https://stackoverflow.com/questions/79759372/vba-vbscript-regular-expressions-crashes

Sub Lookahead()
    Dim re As New VBScript_RegExp_55.RegExp
   ’Set re = GetObject("", "VBScript.RegExp") 'BugFix
    Dim mc As VBScript_RegExp_55.MatchCollection
    re.Global = True
  
    re.Pattern = "([^_]+(?=_))"
    Set mc = re.Execute("abc_def_ghi")
    Debug.Print mc(0).Value
End Sub

The SelenumVBA program does not use them,so I don't think there will be any errors

[6DiegoDiego9]

I use lookaheads in some of my projects, and this (enigmatic) GetObject workaround is a lifesaver! Thanks!

BTW the "New" can be removed if using the workaround

[hanamichi77777]

The Replace bug has been resolved in Office Version2508 Build16.0.19127.20192.
However, the Lookahead bug continues.

[hanamichi77777]

The series of bugs seems to have been affected by the change to Regex to be able to be handled in VBE.
https://devblogs.microsoft.com/microsoft365dev/how-to-prepare-vba-projects-for-vbscript-deprecation/

[GCuser99]

Oh wow - that's big news that RegExp is now part of VBA7 without reference!

[6DiegoDiego9]

In my projects, I would use the following version as a workaround to fix both the Replace and the lookahead bugs, which likely works on both old and new Excel versions:

Sub Workaround()
    Dim re As RegExp
    Set re = GetObject("", "VBScript.RegExp")
    'and never use "VBScript_RegExp_55." when declaring regex objects (Match, MatchCollection, SubMatches)
    ....

(tested with the new Excel)

---

In SeleniumVBA, which does not use lookaheads, we could just remove all the "VBScript_RegExp_55." occurrences in the code to just make it future-proof.
Do you agree?

[GCuser99]

That seems reasonable to me.

[qqzwc]

This really works for me instead of "re.Execute((inputStr)) / re.Execute(CStr(inputStr))"

[hanamichi77777]

A person who appears to be a Microsoft developer posted on StackOverFlow.
https://stackoverflow.com/questions/79759372/vba-vbscript-regular-expressions-crashes

Sorry for the inconvenience, we are working on it. If everything goes well, the fix would get updated starting from next Tuesday. If there is any other code snippet leads crash, please attach here – RuizhiSun-MSFT
(9/12/2025) The statement that the fix is ​​expected to be completed has been removed.

[6DiegoDiego9]

Thanks @hanamichi77777 for the update!

[6DiegoDiego9]

I can't find his original post. Is he aware (and supposedly working on) of the lookahead problem too?

[hanamichi77777]

Please click on the Show 15 more comments link

[6DiegoDiego9]

Ah, thanks! I missed it

[hanamichi77777]

There is an update to Office ver2509 and the "lookaheads bug" in VBA regular expressions has been fixed.

[GCuser99]

In order for SeleniumVBA to work on older versions of Excel/Access, I think we need to do the following for now and can reassess in Phase 2/3 of the deprecation plan. Anyone have a different or better idea?

Sub testSolution()
    Dim re As Object
    Set re = GetObject("", "VBScript.RegExp")
    re.Pattern = "-+"
    Debug.Assert re.test("----")
End Sub

[SanbiVN]

On my computer, GetObject for RegExp is not available.
Because of this error, I tried to embed the Pcre2 library into VBA 64bit based on @jpbro's source code which only works on 32bit.
Although I have to store and load the dll, but in return, it solves a lot of problems, including good performance, I can create modern regular expressions in VBA.

The excel file is attached at the repo:
https://github.com/SanbiVN/VbaPcre2

[Viorel]

How does unavailability manifest?

[SanbiVN]

How does unavailability manifest?

Common error messages when library is not loaded

Run-time error '429':
AcfiveX component can't create object

Sub VBA_VBScript_Regex_test()
    Dim re As RegExp ' include tested New
    Set re = GetObject(, "VBScript.RegExp")
  With re
    .pattern = "(.)(?=.*\1)"
    Debug.Print .test("ss")
  End With
End Sub

[GCuser99]

But what happens if you use Dim re as Object instead of Dim re as RegExp?

[SanbiVN]

But what happens if you use Dim re as Object instead of Dim re as RegExp?

There is no difference

[GCuser99]

So on your system, VBScript.RegExp has already been deprecated?

[GCuser99]

@6DiegoDiego9, I think the problem for @SanbiVN is that he used Set re = GetObject(, "VBScript.RegExp") instead of using Set re = GetObject("", "VBScript.RegExp").

I tried on an older version of Excel just removing the "VBScript_RegExp_55." but still need late binding as shown here. Did you test on an older version of Excel?

[GCuser99]

Note - when I say removing "VBScript_RegExp_55.", I also removed the reference to MS Regular Expressions. Do you mean keeping that reference? If that works for you in the new Excel, then yes, I see what you are proposing would work!

[6DiegoDiego9]

Oh yes I meant that we can just keep the reference (required for the old Excel, and bypassed by the new Excel) and use:

Dim re As New RegExp
Dim matches As MatchCollection, subMatches As SubMatches

or

Dim re As RegExp
Set re = New Regexp
Dim matches As MatchCollection, subMatches As SubMatches

It seems to me that RegExp seamlessly points to the external reference library in the old Excel, and to the new internal object names in the new Excel.
I understand that this is how MS envisioned us making the transition.

[6DiegoDiego9]

About GetObject, to solve the lookahead bug (not needed in SeleniumVBA), yes, I also hope that @SanbiVN will confirm that he tried the wrong one, and that it works for him too with the right one

[SanbiVN]

Previously RegExp on my PC still worked with CreateObject.
This call actually works:

GetObject("", "VBScript.RegExp")

There are two versions of Office on one PC, the old version 2010, TwinBasic IDE, and the VB6 IDE.
The following code always gives an error

GetObject( , "VBScript.RegExp")

[SanbiVN]

Today I got a new Office update, all RegExp errors are fixed.