See the discussion: https://sourceforge.net/p/latexdraw/discussion/525822/thread/f9f6304c/
The problem seems to be the spaces in the file path:
/media/Dados/Dropbox/UFSM/Mestrado/SEM 1/Engenharia de Microondas/seminário 2/figuras/quarterwave_t.svg
Stacktrace:
java.net.MalformedURLException: no protocol: /media/Dados/Dropbox/UFSM/Mestrado/SEM 1/Engenharia de Microondas/seminário 2/figuras/quarterwave_t.svg
at java.net.URL.<init>(Unknown Source)
at java.net.URL.<init>(Unknown Source)
at java.net.URL.<init>(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.setupCurrentEntity(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLVersionDetector.determineDocVersion(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(Unknown Source)
at javax.xml.parsers.DocumentBuilder.parse(Unknown Source)
at net.sf.latexdraw.parsers.svg.SVGDocument.<init>(SVGDocument.java:83)
at net.sf.latexdraw.generators.svg.SVGDocumentGenerator$LoadWorker.doInBackground(SVGDocumentGenerator.java:684)
at net.sf.latexdraw.generators.svg.SVGDocumentGenerator$LoadWorker.doInBackground(SVGDocumentGenerator.java:647)
fixed in: https:/ /github. com/arnobl/ latexdraw/ commit/ 9a25d39023a28a4 ff43678961426c9 210df58597