Merci pour ta réponse Michel!
J'ai bien viré la ligne de code en trop mais le message d'erreur persiste.
Revoilà le code actuel:
Sub EXTRACTION_hr_et_Calcul_sy_et_n(Num As Integer)
Dim NomFichierExcelOuvert As String
Dim I As Integer, J As Integer
NomFichierExcelOuvert = ActiveWorkbook.Name
AddIns("Complément Solver").Installed = True
Application.DisplayAlerts = False
For I = 1 To Workbooks(NomFichierExcelOuvert).Worksheets("CALCUL H & E").Cells(9, 2).Value
J = I + 25
Worksheets("ESSAI " & I).Select
Worksheets("Calcul H & E").Cells(J, 10) = Identification_Valeur_Min()
Worksheets("Calcul H & E").Activate
SolverReset
SolverOk SetCell:="$U$" & J, MaxMinVal:=3, ValueOf:="1", ByChange:="$S$" & J & ",$T$" & J
SolverAdd CellRef:="$T$" & J, Relation:=2, FormulaText:="$Q$" & J & "+$S$" & J
SolverAdd CellRef:="$S$" & J, Relation:=3, FormulaText:="0,01"
SolverOptions MaxTime:=100, _
Iterations:=1000, _
Precision:=0.0000001, _
AssumeLinear:=False, _
StepThru:=False, _
Estimates:=2, _
Derivatives:=2, _
SearchOption:=1, _
IntTolerance:=1, _
Scaling:=False, _
Convergence:=0.00001, _
AssumeNonNeg:=True
Next I
Application.DisplayAlerts = True
End Sub