Font error converting pdf to word

Font error while converting pdf to word.
There is no Serif font, so how can I add that font?

Code

String path = "test.pdf";
Document document = new Document(path);
document.save("test.docx", SaveFormat.DocX);

Exception

java.lang.ExceptionInInitializerError: null
	at com.aspose.pdf.internal.l25l.lc.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l25l.lc.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l25l.lh.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l25l.lv.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l25l.lv.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l25l.lv.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l87p.lv.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l87p.l0l.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l0n.l0l.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l0n.l0l.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l0n.le.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l0y.l0if.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l0n.lc.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l0n.le.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l0y.lk.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l0n.lv.lf(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l0n.lv.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l0n.le.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l0y.lh.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l0n.le.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l0y.lf.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l87p.le.lt(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l0n.lf.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.l3k.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.ADocument.lj(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.ADocument.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.Document.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.ADocument.lI(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.ADocument.save(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.Document.save(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.example.pdftoword.service.Runner.run(Runner.java:24) ~[main/:na]
	at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:704) [spring-boot-1.5.22.RELEASE.jar:1.5.22.RELEASE]
	at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:688) [spring-boot-1.5.22.RELEASE.jar:1.5.22.RELEASE]
	at org.springframework.boot.SpringApplication.afterRefresh(SpringApplication.java:675) [spring-boot-1.5.22.RELEASE.jar:1.5.22.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:301) [spring-boot-1.5.22.RELEASE.jar:1.5.22.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1082) [spring-boot-1.5.22.RELEASE.jar:1.5.22.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1071) [spring-boot-1.5.22.RELEASE.jar:1.5.22.RELEASE]
	at com.example.pdftoword.PdftowordApplication.main(PdftowordApplication.java:10) [main/:na]
Caused by: com.aspose.pdf.internal.ms.System.lh: FontFamily 'Serif' not found
Parameter name: Serif
	at com.aspose.pdf.internal.l67k.l0t.<init>(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l67k.l0t.<init>(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l67k.l0t.<init>(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	at com.aspose.pdf.internal.l67k.l0t.<clinit>(Unknown Source) ~[aspose-pdf-19.1.jar:19.1]
	... 38 common frames omitted

@URLENCE

Please try installing the font in your system and API will pick the required font by Default. In case the font is present in the system and you are still facing this error, please share your sample PDF document with us so that we can test the scenario in our environment and address it accordingly. Also, please try to use 22.5 version of the API which is the latest version.