A first step when encountering execution errors is to test whether your installation is working correctly. An easy way to test the working of various BIDScoin components is to run bidscoin -t in your terminal. Some commonly seen messages are:

The “dcm2niix” command is not recognized

This is an installation problem and means that bidscoin can’t find your dcm2niix executable (just carefully follow the installation instructions)

Could not load the Qt platform plugin “xcb”

This error message may occur on certain Linux platforms when opening the bidseditor. This is an installation issue that may be solved by downgrading your PyQt5 library, e.g. by running pip install --upgrade pyqt5==5.14 in your terminal environment. Another solution might be to use your Linux package manager to install PyQt5, e.g. like this: apt-get install python3-pyqt5 python3-pyqt5.qtx11extras

My Apptainer/Singularity container fails

When running apptainer/singularity on on systems with an older Linux kernel (e.g. older than 3.15) you may get errors such as ImportError: cannot open shared object file: No such file or directory. A working fix may be to add the following line at the end of %post section of the singularity.def file.

strip --remove-section=.note.ABI-tag /usr/lib/x86_64-linux-gnu/

The fix comes from these resources:


The first step in troubleshooting is to look at the warnings and messages printed out in the terminal (they are also save to disk in the bidsfolder/code/bidscoin output folder). Make sure you are ok with the warnings (they are meaningful and not to be ignored) and do not continue with a next step until all errors are resolved.

My bidsmap is empty

After running the bidsmapper, the bidseditor shows an empty bidsmap (i.e no data samples). The most likely cause is that the structure of your raw data repository is not understood by BIDScoin (see data preparation for more info). Another likely cause is that the sub-/ses- prefixes need to be adjusted to your folder names (e.g. when your ). Install and/or add the plugin.

My subject/session labels are wrong

Everything seems to work but the sub-/ses- BIDS labels are not what I want. In the bidseditor main window, play around with the subject regular expressions.

I got an “Unexpected postfix / file conversion result”

This bidscoiner warning message means that the source data was not properly recognised / converted by the plugin. Please search and/or report it on Github issue to resolve it.

I only see “_magnitude1” or “_magnitude2” run-items in my bidsmap

Siemens (and perhaps other manufacturers too) stores all field-map Series in a single Series folder. Hence, when BIDScoin takes a sample from that folder it only sees one of these Series. You don’t need to worry about this, because the dcm2niix plugin will accommodate for this and will look-up the other samples during bidscoiner runtime.

My source-files can no longer be found

You may get the warning “Cannot reliably change the datatype and/or suffix because the source file ‘..’ can no longer be found”. This warning is generated when (1) your source data moved to a different location, or (2) your data is zipped or in DICOMDIR format. This warning can be ignored if you do not need to change the datatype of your run-items anymore (in the bidseditor), because in that case BIDScoin may need access to the source data (to read new properties or attributes). To restore data access for (1), move the data to it’s original location and for (2) use the –store option of bidsmapper to store local copies of the source data samples in the bids output folder.

I have duplicated field maps because of an interrupted session

It may happen that due to irregularities during data acquisition you had to reacquire your field-map for part of your data. In that case the IntendedFor and B0FieldIdentifier/’B0FieldSource` semantics become ambiguous. To handle this situation, you can use json sidecar files to extend the source attributes (see below) or use the limited IntendedFor search as described here and here.

The bidscoiner says that the IntendedFor search gave no results

Even if you have specified the IntendedFor value in the bidseditor, you still get Empty ‘IntendedFor’ field map value in {..}: the search for {..} gave no results. This may be because you hardcoded the IntendedFor value instead of providing a search pattern. Or it may be that you provided a correct search pattern but that for some subjects the target images were not acquired or could not be found (e.g. due to irregularities in the acquisition). Check out the BIDS output session(s) mentioned in the warning(s) and see if and how you should update your IntendedFor search pattern accordingly.

The data of some subjects need to be treated (mapped) differently

Sometimes you may have irregularities in your data that make that you would like make exceptions for run-items of certain subjects. There are different ways to do this but most likely the best way to do this is to add a json sidecar file to the source data of those run-items. In the json sidecar file you can store an attribute key-value pair to overrule or extend the original attribute value of the source data. For instance, if your fmri run was acquired with the wrong task presentation, e.g. task2 instead of task1, you can add SeriesDescription: task2 to the sidecar file to overrule SeriesDescription: task1 in the DICOM header (to make a more specific exception that shows up as a new run-item in the bidsmap you can change it to e.g. task1_exception).

More help

If this guide doesn’t help to solve your problem, then you can search on github for open and/or closed issues to see if anyone else has encountered similar problems before. If not, feel free to help yourself and others by opening a new github issue.