# Reporting a bug

## Before filing a bug report

If you think you have found a bug in Bio-Formats, the first thing to do is update your version of Bio-Formats to the latest version to check if the problem has already been addressed. The Fiji updater will automatically do this for you, while in ImageJ you can select Plugins ‣ Bio-Formats ‣ Update Bio-Formats Plugins.

You can also download the latest version of Bio-Formats from the OME website.

## Common issues to check

- If you get an error message similar to:

      java.lang.UnsupportedClassVersionError: loci/plugins/LociImporter :
      Unsupported major.minor version 52.0

      This plugin requires Java 1.8 or later.

  you need to upgrade your system Java version to Java 8 or above, or download a new version of ImageJ/Fiji bundled with Java 8.

- If your 12, 14 or 16-bit images look all black when you open them, typically the problem is that the pixel values are very, very small relative to the maximum possible pixel value (4095, 16383, and 65535, respectively), so when displayed the pixels are effectively black. In ImageJ/Fiji, this is fixable by checking the “Autoscale” option; with the command line tools, the “-autoscale -fast” options should work.

- If the file is very, very small (4096 bytes) and any exception is generated when reading the file, then make sure it is not a Mac OS X resource fork. The ‘file’ command should tell you:

      $ file /path/to/suspicious-file
      suspicious-file: AppleDouble encoded Macintosh file

- If you get an `OutOfMemory` or `NegativeArraySize` error message when attempting to open an SVS or JPEG-2000 file then the amount of pixel data in a single image plane exceeds the amount of memory allocated to the JVM or 2 GB, respectively. For the former, you can increase the amount of memory allocated; in the latter case, you will need to open the image in sections. If you are using Bio-Formats as a library, this means using the `openBytes(int, int, int, int, int)` method in loci.formats.IFormatReader. If you are using Bio-Formats within ImageJ, you can use the Crop on import option.

  Note that JPEG-2000 is a very efficient compression algorithm - thus the size of the file on disk will be substantially smaller than the amount of memory required to store the uncompressed pixel data. It is not uncommon for a JPEG-2000 or SVS file to occupy less than 200 MB on disk, and yet have over 2 GB of uncompressed pixel data.

## Sending a bug report

If you can still reproduce the bug after updating to the latest version of Bio-Formats, and your issue does not relate to anything listed above or noted on the relevant file format page, please send a bug report to the forums. You can upload sample files to the Bio-Formats Zenodo community, or for files over 50 GB, we can provide you with an FTP server address.

To ensure that any inquiries you make are resolved promptly, please include the following information:

- Exact error message. Copy and paste any error messages into the text of your email. Alternatively, attach a screenshot of the relevant windows.

- Version information. Indicate which release of Bio-Formats, which operating system, and which version of Java you are using.

- Non-working data. If possible, please send a non-working file that may be made public under a liberal license, at least CC-BY 4.0. This helps us ensure that the problem is fixed for next release and will not reappear in later releases. Providing data that cannot be made public is strongly discouraged. See Receipt of Sample Data.

- Metadata and screenshots. If possible, include any additional information about your data. We are especially interested in the expected dimensions (width, height, number of channels, Z slices, and timepoints). Screenshots of the image being successfully opened in other software are also useful.

- Format details. If you are requesting support for a new format, we ask that you send as much data as you have regarding this format (sample files, specifications, vendor/manufacturer information, etc.). This helps us to better support the format and ensures future versions of the format are also supported.

Please be patient - it may be a few days until you receive a response, but we reply to every email inquiry we receive.