MemoryStream - Cannot access a closed Stream

Question

Hi why  using  var sw   new StreamWriter ms   returns Cannot access a closed Stream exception  Memory Stream is on top of this code    using  var ms   new MemoryStream          using  var sw   new StreamWriter ms                                  sw WriteLine  data            sw WriteLine  data 2            ms Position   0          using  var sr   new StreamReader ms                         Console WriteLine sr ReadToEnd                                               error here     What the best way to fix it   Thanks

User · Answer

The problem is this block   using  var sr   new StreamReader ms         Console WriteLine sr ReadToEnd                                 When the StreamReader is closed  after leaving the using   it closes it s underlying stream as well  so now the MemoryStream is closed  When the StreamWriter gets closed  it tries to flush everything to the MemoryStream  but it is closed   You should consider not putting the StreamReader in a using block

User · Answer

Since  net45 you can use the LeaveOpen constructor argument of StreamWriter and still use the using statement  Example   using  var ms   new MemoryStream          using  var sw   new StreamWriter ms  Encoding UTF8  1024  true                 sw WriteLine  data            sw WriteLine  data 2                   ms Position   0      using  var sr   new StreamReader ms                 Console WriteLine sr ReadToEnd

User · Answer

In my case  admittedly very arcane and not likely to be reproduced often   this was causing the problem  this code is related to PDF generation using iTextSharp    PdfPTable tblDuckbilledPlatypi   new PdfPTable 3   float   DuckbilledPlatypiRowWidths   new float     42f  76f    tblDuckbilledPlatypi SetWidths DuckbilledPlatypiRowWidths     The declaration of a 3-celled columned table  and then setting only two vals for the width was what caused the problem  apparently  Once I changed  PdfPTable 3   to  PdfPTable 2   the problem went the way of the convection oven

User · Answer

When the using   for your StreamReader is ending  it s disposing the object and closing the stream  which your StreamWriter is still trying to use

User · Answer

when it gets out from the using statement the Dispose method will be called automatically closing the stream  try the below   using  var ms   new MemoryStream          var sw   new StreamWriter ms            sw WriteLine  data            sw WriteLine  data 2            ms Position   0          using  var sr   new StreamReader ms                         Console WriteLine sr ReadToEnd

User · Answer

This is because the StreamReader closes the underlying stream automatically when being disposed of  The using statement does this automatically    However  the StreamWriter you re using is still trying to work on the stream  also  the using statement for the writer is now trying to dispose of the StreamWriter  which is then trying to close the stream    The best way to fix this is  don t use using and don t dispose of the StreamReader and StreamWriter  See this question   using  var ms   new MemoryStream          var sw   new StreamWriter ms       var sr   new StreamReader ms        sw WriteLine  data        sw WriteLine  data 2        ms Position   0       Console WriteLine sr ReadToEnd                                 If you feel bad about sw and sr being garbage-collected without being disposed of in your code  as recommended   you could do something like that   StreamWriter sw   null  StreamReader sr   null   try       using  var ms   new MemoryStream                  sw   new StreamWriter ms           sr   new StreamReader ms            sw WriteLine  data            sw WriteLine  data 2            ms Position   0           Console WriteLine sr ReadToEnd                                     finally       if  sw    null  sw Dispose        if  sr    null  sr Dispose

[c#] MemoryStream - Cannot access a closed Stream

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