Fiji macro fails to open images

Hello.
I’ve been trying to run my macros on FIJI, but it fails to open any image. I get a message called “Exception”, that looks like this:

(Fiji Is Just) ImageJ 2.1.0/1.53e; Java 1.8.0_66 [64-bit]; Windows 10 10.0; 299MB of 6006MB (4%)
java.lang.NoClassDefFoundError: org/apache/xml/serializer/TreeWalker
at org.apache.xalan.processor.TransformerFactoryImpl.newTransformer(TransformerFactoryImpl.java:818)
at loci.common.xml.XMLTools.writeXML(XMLTools.java:609)
at loci.common.xml.XMLTools.writeXML(XMLTools.java:593)
at loci.common.xml.XMLTools.dumpXML(XMLTools.java:293)
at loci.common.xml.XMLTools.dumpXML(XMLTools.java:272)
at ome.xml.meta.AbstractOMEXMLMetadata.dumpXML(AbstractOMEXMLMetadata.java:112)
at ome.xml.meta.OMEXMLMetadataImpl.dumpXML(OMEXMLMetadataImpl.java:105)
at loci.formats.ome.OMEPyramidStore.dumpXML(OMEPyramidStore.java:81)
at loci.formats.services.OMEXMLServiceImpl.getOMEXML(OMEXMLServiceImpl.java:468)
at loci.plugins.in.ImportProcess.getOMEXML(ImportProcess.java:264)
at loci.plugins.in.ImagePlusReader.createFileInfo(ImagePlusReader.java:521)
at loci.plugins.in.ImagePlusReader.readImage(ImagePlusReader.java:314)
at loci.plugins.in.ImagePlusReader.readImages(ImagePlusReader.java:243)
at loci.plugins.in.ImagePlusReader.readImages(ImagePlusReader.java:221)
at loci.plugins.in.ImagePlusReader.openImagePlus(ImagePlusReader.java:116)
at loci.plugins.in.Importer.readPixels(Importer.java:149)
at loci.plugins.in.Importer.run(Importer.java:86)
at loci.plugins.LociImporter.run(LociImporter.java:78)
at ij.IJ.runUserPlugIn(IJ.java:240)
at ij.IJ.runPlugIn(IJ.java:203)
at ij.Executer.runCommand(Executer.java:150)
at ij.Executer.run(Executer.java:68)
at ij.IJ.run(IJ.java:322)
at ij.IJ.run(IJ.java:333)
at ij.macro.Functions.doRun(Functions.java:686)
at ij.macro.Functions.doFunction(Functions.java:98)
at ij.macro.Interpreter.doStatement(Interpreter.java:278)
at ij.macro.Interpreter.doBlock(Interpreter.java:712)
at ij.macro.Interpreter.doStatement(Interpreter.java:323)
at ij.macro.Interpreter.doFor(Interpreter.java:634)
at ij.macro.Interpreter.doStatement(Interpreter.java:305)
at ij.macro.Interpreter.doStatements(Interpreter.java:264)
at ij.macro.Interpreter.run(Interpreter.java:160)
at ij.macro.Interpreter.run(Interpreter.java:93)
at ij.macro.Interpreter.run(Interpreter.java:104)
at ij.plugin.Macro_Runner.runMacro(Macro_Runner.java:162)
at ij.IJ.runMacro(IJ.java:158)
at ij.IJ.runMacro(IJ.java:147)
at net.imagej.legacy.IJ1Helper$3.call(IJ1Helper.java:1148)
at net.imagej.legacy.IJ1Helper$3.call(IJ1Helper.java:1144)
at net.imagej.legacy.IJ1Helper.runMacroFriendly(IJ1Helper.java:1095)
at net.imagej.legacy.IJ1Helper.runMacro(IJ1Helper.java:1144)
at net.imagej.legacy.plugin.IJ1MacroEngine.eval(IJ1MacroEngine.java:145)
at org.scijava.script.ScriptModule.run(ScriptModule.java:157)
at org.scijava.module.ModuleRunner.run(ModuleRunner.java:165)
at org.scijava.module.ModuleRunner.call(ModuleRunner.java:124)
at org.scijava.module.ModuleRunner.call(ModuleRunner.java:63)
at org.scijava.thread.DefaultThreadService.lambda$wrap$2(DefaultThreadService.java:225)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.ClassNotFoundException: org.apache.xml.serializer.TreeWalker
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
… 52 more

I’ve tried to run macros that I have been using for a long time, work on my machine, for sure. They also work on other computers (now).
I’ve also tried switching to older versions of Fiji (from 1.53 to 1.51, for example), but nothing works.
It’s probably something trivial, but I can’t seem to be able to solve it. Does anyone have an idea?
Best,

George