JPEG Library Error: Not a JPEG file

Last Published: April 25, 2020

Error Message

When trying to access a ArcIMS image service using ArcPad, ArcPad crashes with an error window titled "JPEG Library Error" stating:

"Not a JPEG file:"


ArcPad expects JPEG images from ArcIMS map services. This error occurs when the ArcIMS map service returns a different type of output image, such as PNG.

As a precaution, ArcPad's requests automatically include the <OUTPUT> tag, which allows ArcPad to specifically request a JPEG image, regardless of the type of image the map service usually produces. However, by default the <OUTPUT> tag is blocked by the ArcIMS server as a security measure.

Solution or Workaround

Please note: The solution to this issue must be done on the ArcIMS server! There is no client-side solution for this error.

  1. Review the ArcXML Programmers Reference Guide for more information on the <OUTPUT> tag and its security restrictions. Also check the ArcIMS Help under
    Using ArcIMS
    Administering the ArcIMS Servlet Connector
    ArcIMS Servlet connector properties

  2. Following the guidelines in the documentation mentioned above, modify the Esrimap_prop file setting as shown here:

    spatialServer.AllowResponsePath can be left as False

  3. Save and close the modified Esrimap_prop file.
  4. Stop and restart your webserver to make the modification take effect.

Article ID:000005437

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