import arcpy
#Set join parameter variables
inFeatures = arcpy.GetParameterAsText(0) #This is a feature class of forest roads. It is a feature class data type in the script tool in ArcGIS
inField = arcpy.GetParameterAsText(1) #This is the join field in the feature class. This is a field data type in the stript tool in ArcGIS
joinTable = arcpy.GetParameterAsText(2) #This is a table of buffer widths by road class.  This is a table data type in the script tool in ArcGIS
joinField = arcpy.GetParameterAsText(3)  #This is the join field in the buffer table. This is a field data type in the script tool in ArcGIS
arcpy.MakeFeatureLayer_management(inFeatures,"inFeatures_lyr") #make feature layer from feature class
#Join road feature class to buffer distance table
arcpy.JoinField_management("inFeatures_lyr", inField, joinTable, joinField)
#Select roads that intersect the stdsm feature class
stdsM = arcpy.GetParameterAsText(4)  #this is a polygon feature class. It is a feature class data type in ArcGIS
arcpy.MakeFeatureLayer_management(stdsM,"stdsM_lyr") #make feature layer from feature class
arcpy.SelectLayerByLocation_management("inFeatures_lyr", "INTERSECT", "stdsM_lyr")
#create output parameter and buffer roads
outFeatures = arcpy.GetParameterAsText(5)  #This is the output feature class of road buffers.  This is a feature class data type in the script tool in ArcGIS
arcpy.Buffer_analysis("infeatures_lyr", outFeatures, "DISTANCE")
#Remove join from Roads
arcpy.RemoveJoin_management("inFeatures_lyr")
#Add identifying field to buffer layer and calculate a value
arcpy.MakeFeatureLayer_management(outFeatures, "outFeatures_lyr")
arcpy.AddField_management("outFeatures_lyr", "BUFFER", "TEXT")

Messages Executing: StdsmToStdsl I:GISDATA_ScriptingStdsmToStdsl.gdbForestRoads RDCLASS I:GISDATA_ScriptingStdsmToStdsl.gdbBufferDist RDCLASS I:GISDATA_ScriptingStdsmToStdsl.gdbstdsm I:GISDATA_ScriptingStdsmToStdsl.gdbForestRoads_Buffer Start Time: Fri Jun 02 15:10:53 2017 Running script StdsmToStdsl... Failed script StdsmToStdsl...

Traceback (most recent call last):   File "I:GISDATA_ScriptingStdsmToStdsl.py", line 17, in <module>
    arcpy.Buffer_analysis("infeatures_lyr", outFeatures, "DISTANCE")   File "c:program files (x86)arcgisdesktop10.3arcpyarcpyanalysis.py", line 692, in Buffer
    raise e ExecuteError: ERROR 999999: Error executing function. Failed to execute (Buffer).


Failed to execute (StdsmToStdsl). Failed at Fri Jun 02 15:23:59 2017 (Elapsed Time: 13 minutes 6 seconds)

import arcpy
arcpy.env.workspace = "I:/GISDATA/_Scripting/StdsmToStdsl.gdb"
arcpy.Buffer_analysis("ForestRoads", "ForestRoadsBuffer", "DISTANCE", "FULL", "ROUND", "ALL")