Below are excerpts from qa-tx.html showing...
 - an expansion request on a value set that includes all codes from http://hl7.org/fhir/sid/ndc (500 - Internal Server Error response)
 - expansion request on a value set that includes a single ndc from http://hl7.org/fhir/sid/ndc (200 - OK response)


---------------------------------------------------------------------------
Expansion fails when the value set includes all codes from http://hl7.org/fhir/sid/ndc
----------------------------------------------------------------------------
REQUEST:

POST http://tx.fhir.org/r4/ValueSet/$expand?_limit=1000&_incomplete=true HTTP/1.0
User-Agent: Java FHIR Client for FHIR
Accept: application/fhir+xml
Content-Type: application/fhir+xml;charset=UTF-8
Accept-Charset: UTF-8


<?xml version="1.0" encoding="UTF-8"?>
<Parameters xmlns="http://hl7.org/fhir">
   <parameter>
      <name value="profile-url" />
      <valueString value="dc8fd4bc-091a-424a-8a3b-6198ef146891" />
   </parameter>
   <parameter>
      <name value="includeDefinition" />
      <valueBoolean value="false" />
   </parameter>
   <parameter>
      <name value="excludeNested" />
      <valueBoolean value="false" />
   </parameter>
   <parameter>
      <name value="valueSet" />
      <resource>
         <ValueSet>
            <status value="active" />
            <compose>
               <include>
                  <system value="http://hl7.org/fhir/sid/ndc" />
               </include>
            </compose>
         </ValueSet>
      </resource>
   </parameter>
   <parameter>
      <name value="_limit" />
      <valueString value="1000" />
   </parameter>
   <parameter>
      <name value="_incomplete" />
      <valueString value="true" />
   </parameter>
</Parameters>

-----------------------------------------------------------------------------
RESPONSE:
HTTP/1.1 500 Internal Server Error

<?xml version="1.0" encoding="UTF-8"?>
<OperationOutcome xmlns="http://hl7.org/fhir">
   <text>
      <status value="generated" />
      <div xmlns="http://www.w3.org/1999/xhtml">
         <p>Access violation at address 0000000000E97189 in module 'FHIRServer.exe'. Read of address 000000000000001C</p>
      </div>
   </text>
   <issue>
      <severity value="error" />
      <details>
         <text value="Access violation at address 0000000000E97189 in module 'FHIRServer.exe'. Read of address 000000000000001C" />
      </details>
      <diagnostics value="(0000000000A96189){FHIRServer.exe} [0000000000E97189] FHIR.R4.Json.TFHIRJsonParser.ParseDocumentManifestProperties (Line 25038, &quot;FHIR.R4.Json.pas&quot; + 7) + $89&#xD;&#xA;(000000000592F59C){FHIRServer.exe} [0000000005D3059C]&#xD;&#xA;(00000000059314F1){FHIRServer.exe} [0000000005D324F1]&#xD;&#xA;(000000000004B6C7){FHIRServer.exe} [000000000044C6C7] System.SysUtils.StringReplace + $277&#xD;&#xA;(000000000004BF4B){FHIRServer.exe} [000000000044CF4B] System.SysUtils.FindCmdLineSwitch + $3B&#xD;&#xA;(0000000005920FE9){FHIRServer.exe} [0000000005D21FE9]&#xD;&#xA;(00000000059212B5){FHIRServer.exe} [0000000005D222B5]&#xD;&#xA;(0000000000010D4E){FHIRServer.exe} [0000000000411D4E] System.@DelphiExceptionHandler + $2DE&#xD;&#xA;(000000000009245D){ntdll.dll   } [00007FFF7F6B345D] Unknown function at __chkstk + $9D&#xD;&#xA;(0000000000053937){ntdll.dll   } [00007FFF7F674937] Unknown function at RtlRaiseException + $F67&#xD;&#xA;(00000000000915EA){ntdll.dll   } [00007FFF7F6B25EA] KiUserExceptionDispatcher + $3A&#xD;&#xA;(0000000000A96189){FHIRServer.exe} [0000000000E97189] FHIR.R4.Json.TFHIRJsonParser.ParseDocumentManifestProperties (Line 25038, &quot;FHIR.R4.Json.pas&quot; + 7) + $89&#xD;&#xA;(0000000000908FBF){FHIRServer.exe} [0000000000D09FBF] FHIR.R4.Xml.TFHIRXmlComposer.ComposeMessageDefinitionChildren (Line 38749, &quot;FHIR.R4.Xml.pas&quot; + 29) + $20&#xD;&#xA;(0000000000906B4D){FHIRServer.exe} [0000000000D07B4D] FHIR.R4.Xml.TFHIRXmlParser.ParseMessageDefinitionFocus (Line 38523, &quot;FHIR.R4.Xml.pas&quot; + 4) + $3&#xD;&#xA;(0000000000905980){FHIRServer.exe} [0000000000D06980] FHIR.R4.Xml.TFHIRXmlParser.ParseMedicinalProductUndesirableEffectPopulation (Line 38398, &quot;FHIR.R4.Xml.pas&quot; + 15) + $0&#xD;&#xA;(0000000000B18261){FHIRServer.exe} [0000000000F19261] FHIR.R4.Json.TFHIRJsonParser.ParseMedicinalProductDeviceSpecProperties (Line 39303, &quot;FHIR.R4.Json.pas&quot; + 19) + $19&#xD;&#xA;(0000000000B17A9A){FHIRServer.exe} [0000000000F18A9A] FHIR.R4.Json.TFHIRJsonParser.ParseMedicinalProductDeviceSpecMaterial (Line 39234, &quot;FHIR.R4.Json.pas&quot; + 6) + $A&#xD;&#xA;(00000000039D173A){FHIRServer.exe} [0000000003DD273A] Vcl.Themes.{System.Generics.Collections}TDictionary&lt;System.string,Vcl.Themes.TStyleManager.TSourceInfo&gt;.Create + $A&#xD;&#xA;(0000000000BE37B0){FHIRServer.exe} [0000000000FE47B0] FHIR.R4.Json.TFHIRJsonComposer.ComposeBase (Line 62384, &quot;FHIR.R4.Json.pas&quot; + 1465) + $1B&#xD;&#xA;(0000000003A27064){FHIRServer.exe} [0000000003E28064] Vcl.Forms.TApplication.Destroy + $204&#xD;&#xA;(0000000000BDBE89){FHIRServer.exe} [0000000000FDCE89] FHIR.R4.Json.TFHIRJsonParser.ParseDataType (Line 60892, &quot;FHIR.R4.Json.pas&quot; + 57) + $3&#xD;&#xA;(0000000005740D21){FHIRServer.exe} [0000000005B41D21]&#xD;&#xA;(0000000005737186){FHIRServer.exe} [0000000005B38186]&#xD;&#xA;(0000000005733616){FHIRServer.exe} [0000000005B34616]&#xD;&#xA;(0000000005755506){FHIRServer.exe} [0000000005B56506]&#xD;&#xA;(00000000006C9339){FHIRServer.exe} [0000000000ACA339] FHIR.Web.GraphQL..{System.Generics.Collections}TList&lt;FHIR.Web.GraphQL.TGraphQLArgument&gt; (Line 43, &quot;System.Generics.Defaults.pas&quot; + 0) + $3507&#xD;&#xA;(00000000006CACBA){FHIRServer.exe} [0000000000ACBCBA] FHIR.Web.GraphQL..{System.Generics.Collections}TList&lt;FHIR.Web.GraphQL.TGraphQLValue&gt; (Line 43, &quot;System.Generics.Defaults.pas&quot; + 0) + $4E88&#xD;&#xA;(0000000000431EB9){FHIRServer.exe} [0000000000832EB9] FHIR.Base.Common..{FHIR.Support.Base}TMoveArrayManager&lt;FHIR.Base.Common.TFHIRSearchParamDefinitionW&gt; (Line 4111, &quot;System.Generics.Collections.pas&quot; + 0) + $AAEC&#xD;&#xA;(000000000042FECA){FHIRServer.exe} [0000000000830ECA] FHIR.Base.Common..{FHIR.Support.Base}TMoveArrayManager&lt;FHIR.Base.Common.TFhirBundleEntryW&gt; (Line 4111, &quot;System.Generics.Collections.pas&quot; + 0) + $8AFD&#xD;&#xA;(0000000000433EAB){FHIRServer.exe} [0000000000834EAB] FHIR.Base.Common..{System.Generics.Collections}TList&lt;FHIR.Base.Common.TFhirParametersParameterW&gt;.TEnumerator (Line 4111, &quot;System.Generics.Collections.pas&quot; + 0) + $CADE&#xD;&#xA;(000000000043314B){FHIRServer.exe} [000000000083414B] FHIR.Base.Common..{System.Generics.Collections}TList&lt;FHIR.Base.Common.TFHIRSearchParamDefinitionW&gt; (Line 4111, &quot;System.Generics.Collections.pas&quot; + 0) + $BD7E&#xD;&#xA;(00000000001396F3){FHIRServer.exe} [000000000053A6F3] System.Classes.{System.Generics.Collections}TList&lt;System.IInterface&gt;.DoGetEnumerator + $3&#xD;&#xA;(000000000001219D){FHIRServer.exe} [000000000041319D] System.ThreadWrapper + $4D&#xD;&#xA;(00000000000003D2){KERNEL32.DLL} [00007FFF7F4E13D2] BaseThreadInitThunk + $22&#xD;&#xA;(00000000000144F4){ntdll.dll   } [00007FFF7F6354F4] RtlUserThreadStart + $34&#xD;&#xA;" />
   </issue>
</OperationOutcome>


----------------------------------------------------------------------
----------------------------------------------------------------------
Expansion works when limiting the value set to a single NDC
-----------------------------------------------------------------------
POST http://tx.fhir.org/r4/ValueSet/$expand?_limit=1000&_incomplete=true HTTP/1.0
User-Agent: Java FHIR Client for FHIR
Accept: application/fhir+xml
Content-Type: application/fhir+xml;charset=UTF-8
Accept-Charset: UTF-8


<?xml version="1.0" encoding="UTF-8"?>
<Parameters xmlns="http://hl7.org/fhir">
   <parameter>
      <name value="profile-url" />
      <valueString value="dc8fd4bc-091a-424a-8a3b-6198ef146891" />
   </parameter>
   <parameter>
      <name value="includeDefinition" />
      <valueBoolean value="false" />
   </parameter>
   <parameter>
      <name value="excludeNested" />
      <valueBoolean value="false" />
   </parameter>
   <parameter>
      <name value="valueSet" />
      <resource>
         <ValueSet>
            <status value="active" />
            <compose>
               <include>
                  <system value="http://hl7.org/fhir/sid/ndc" />
                  <concept>
                     <code value="0777-3104-02" />
                     <display value="Prozac" />
                  </concept>
               </include>
            </compose>
         </ValueSet>
      </resource>
   </parameter>
   <parameter>
      <name value="_limit" />
      <valueString value="1000" />
   </parameter>
   <parameter>
      <name value="_incomplete" />
      <valueString value="true" />
   </parameter>
</Parameters>


----------------------------------------------------------------
RESPONSE:
HTTP/1.1 200 OK