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Data Loader Error - Java Heap Space

I am trying to import Attachments exported from another Org into this Org. Shortly after attempting to 'Finish' the import using the DataLoader (v17), I am getting a Java Heap Space error. I have tried rebooting the PC. None of the files are larger than 5MB.


Any suggestions would be greatly appreciated.


Is this an ongoing integration? You may want to consider Salesforce to Salesforce now that Attachments are supported.


Hope that helps,



Shilyer,  thanks for your reply.  No, this is a one time org to org merge.  We are using Data Loader to move all the records from one org to another.  Our last step is Attachments.


I was able to resolve the 'Java Heap Space' error.  It appears to be have been caused by a corrupted .csv file that was being interpretted as a .SYLK file.


Hi mbrus02,May i know how you resolve the java heap space error. .when i am trying to export all data from SF through Apex Data Loader ,i am geting this error..It will be so useful if u tell how you resolved.Thanks in advance. 




I don't remember the specific, it was over 2 years ago.  However, from the message:  "I was able to resolve the 'Java Heap Space' error.  It appears to be have been caused by a corrupted .csv file that was being interpretted as a .SYLK file."


Hope it helps.


Mark Bruso


Hi There,


A Java heap space error really isn't related to a corrupt CSV. All extracts you do from a SF organization, when opened in Excel or other programs are initially interpreted as a SLVK file.


A Java heap space error occurs because the Java VM being used to run the data processes has run out of space that it uses in your system RAM to temporarily store the data. You can increase your Java heap size in a couple ways. The easiest is to add the arguments to a shortcut on your desktop. We migrate hundreds of gigs of data in and out of Salesorce on a regular basis.


The important thing to remember here is Java heap space is temporarily stored in your system RAM, so if you are running on a machine with 1 or 2GB of RAM you will likely run into Java errors when it tries to create the Java vm after you have raised it.


For example, the standard heap space is about 256mb, we increase this size on our data workstations to 1024mb to 2048mb range, java has a limitation on some systems about creating a vm with a heap size over 2GB. So to set the difference make sure your on a machine with at least 4-6GB of RAM and set the Java flags to something like -Xms1024m -Xmx1596m using the instructions from this page:


We do this stuff a lot, I really hope this helps you and future users.