Exception reading PDF files in PagePdfDocumentReader

[GrantGochnauer]

Bug description
Parsing a publically available PDF file (https://www.novo-pi.com/ozempic.pdf) results in an exception:

Failed to ingest PDF file ozempic-pi.pdf
java.lang.RuntimeException: Failed to ingest PDF file ozempic-pi.pdf
	at com.vodori.platform.ai.advisor.service.DocumentIngestionService.ingestSupportingDocuments(DocumentIngestionService.java:103)
	at com.vodori.platform.ai.advisor.DocumentIngestionTest.setUp(DocumentIngestionTest.java:56)
	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596)
Caused by: java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
	at java.base/jdk.internal.util.Preconditions$1.apply(Preconditions.java:55)
	at java.base/jdk.internal.util.Preconditions$1.apply(Preconditions.java:52)
	at java.base/jdk.internal.util.Preconditions$4.apply(Preconditions.java:213)
	at java.base/jdk.internal.util.Preconditions$4.apply(Preconditions.java:210)
	at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:98)
	at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:106)
	at java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:302)
	at java.base/java.lang.String.checkIndex(String.java:4832)
	at java.base/java.lang.StringLatin1.charAt(StringLatin1.java:46)
	at java.base/java.lang.String.charAt(String.java:1555)
	at org.springframework.ai.reader.pdf.layout.CharacterFactory.getCharacterFromTextPosition(CharacterFactory.java:97)
	at org.springframework.ai.reader.pdf.layout.CharacterFactory.createCharacterFromTextPosition(CharacterFactory.java:46)
	at org.springframework.ai.reader.pdf.layout.ForkPDFLayoutTextStripper.writeLine(ForkPDFLayoutTextStripper.java:114)
	at org.springframework.ai.reader.pdf.layout.ForkPDFLayoutTextStripper.writeTextPositionList(ForkPDFLayoutTextStripper.java:148)
	at org.springframework.ai.reader.pdf.layout.ForkPDFLayoutTextStripper.iterateThroughTextList(ForkPDFLayoutTextStripper.java:136)
	at org.springframework.ai.reader.pdf.layout.ForkPDFLayoutTextStripper.writePage(ForkPDFLayoutTextStripper.java:85)
	at org.springframework.ai.reader.pdf.layout.PDFLayoutTextStripperByArea.writePage(PDFLayoutTextStripperByArea.java:150)
	at org.apache.pdfbox.text.PDFTextStripper.processPage(PDFTextStripper.java:380)
	at org.springframework.ai.reader.pdf.layout.ForkPDFLayoutTextStripper.processPage(ForkPDFLayoutTextStripper.java:68)
	at org.springframework.ai.reader.pdf.layout.PDFLayoutTextStripperByArea.extractRegions(PDFLayoutTextStripperByArea.java:123)
	at org.springframework.ai.reader.pdf.PagePdfDocumentReader.get(PagePdfDocumentReader.java:141)
	at org.springframework.ai.reader.pdf.PagePdfDocumentReader.get(PagePdfDocumentReader.java:48)
	at org.springframework.ai.document.DocumentReader.read(DocumentReader.java:25)
	at com.vodori.platform.ai.advisor.service.DocumentIngestionService.ingestSupportingDocuments(DocumentIngestionService.java:79)
	... 3 more

Environment

• Spring AI 1.0.M8
• Spring Boot 3.4.5
• MacOS
• Java 21

Steps to reproduce
Pass in the PDF linked above and call (which I pulled from the Spring AI docs)

List<Document> pages = new PagePdfDocumentReader(resource,
            PdfDocumentReaderConfig.builder().withPageTopMargin(0).withPageExtractedTextFormatter(ExtractedTextFormatter.builder().withNumberOfTopTextLinesToDelete(0).build())
                .withPagesPerDocument(1).build()).read();

Expected behavior
List of pages.

[GrantGochnauer]

OpenAI's codex suggested to modify:

src/main/java/org/springframework/ai/reader/pdf/layout/CharacterFactory.java

"Override of CharacterFactory to guard against empty unicode strings."

[sunyuhan1998]

I followed the reproduction code you provided, but it seems unable to reproduce the issue in my environment. Below is my code and the log obtained from executing it.

Code:
List<Document> pages = new PagePdfDocumentReader("https://www.novo-pi.com/ozempic.pdf",PdfDocumentReaderConfig.builder().withPageTopMargin(0).withPageExtractedTextFormatter(ExtractedTextFormatter.builder().withNumberOfTopTextLinesToDelete(0).build()).withPagesPerDocument(1).build()).read();

Logs:

11:31:00.277 [main] INFO org.springframework.ai.reader.pdf.PagePdfDocumentReader -- Processing PDF page: 1 11:31:00.335 [main] INFO org.springframework.ai.reader.pdf.PagePdfDocumentReader -- Processing PDF page: 2 11:31:00.371 [main] INFO org.springframework.ai.reader.pdf.PagePdfDocumentReader -- Processing PDF page: 3 11:31:00.397 [main] INFO org.springframework.ai.reader.pdf.PagePdfDocumentReader -- Processing PDF page: 4 11:31:00.425 [main] INFO org.springframework.ai.reader.pdf.PagePdfDocumentReader -- Processing PDF page: 5 11:31:00.445 [main] INFO org.springframework.ai.reader.pdf.PagePdfDocumentReader -- Processing PDF page: 6 11:31:00.464 [main] INFO org.springframework.ai.reader.pdf.PagePdfDocumentReader -- Processing PDF page: 7 11:31:00.487 [main] INFO org.springframework.ai.reader.pdf.PagePdfDocumentReader -- Processing PDF page: 8 11:31:00.502 [main] INFO org.springframework.ai.reader.pdf.PagePdfDocumentReader -- Processing PDF page: 9 11:31:00.514 [main] INFO org.springframework.ai.reader.pdf.PagePdfDocumentReader -- Processing PDF page: 10 11:31:00.572 [main] WARN org.apache.fontbox.cff.Type1CharString -- Unknown charstring command in glyph space of font LZZKUG+FrutigerLTPro-Bold 11:31:00.572 [main] WARN org.apache.fontbox.cff.Type1CharString -- Unknown charstring command in glyph space of font LZZKUG+FrutigerLTPro-Bold 11:31:00.573 [main] WARN org.apache.fontbox.cff.Type1CharString -- Unknown charstring command in glyph space of font LZZKUG+FrutigerLTPro-Black 11:31:00.573 [main] WARN org.apache.fontbox.cff.Type1CharString -- Unknown charstring command in glyph space of font LZZKUG+FrutigerLTPro-Black 11:31:00.573 [main] WARN org.apache.fontbox.cff.Type1CharString -- Unknown charstring command in glyph space of font LZZKUG+FrutigerLTPro-Black 11:31:00.666 [main] WARN org.apache.fontbox.cff.Type1CharString -- Unknown charstring command in glyph space of font LZZKUG+FrutigerLTPro-Bold 11:31:00.666 [main] WARN org.apache.fontbox.cff.Type1CharString -- Unknown charstring command in glyph space of font LZZKUG+FrutigerLTPro-Bold 11:31:00.666 [main] WARN org.apache.fontbox.cff.Type1CharString -- Unknown charstring command in glyph space of font LZZKUG+FrutigerLTPro-Black 11:31:00.666 [main] WARN org.apache.fontbox.cff.Type1CharString -- Unknown charstring command in glyph space of font LZZKUG+FrutigerLTPro-Black 11:31:00.666 [main] WARN org.apache.fontbox.cff.Type1CharString -- Unknown charstring command in glyph space of font LZZKUG+FrutigerLTPro-Black 11:31:00.675 [main] INFO org.springframework.ai.reader.pdf.PagePdfDocumentReader -- Processing 16 pages

[GrantGochnauer]

Interesting, I made a separate test case and used your line of code but still get the same issue - even when I pull directly from the web url. Are you testing against 1.0M8 or a different nightly build?

This is my gradle file:

plugins {
    id 'java'
    id 'org.springframework.boot' version '3.4.5'
    id 'io.spring.dependency-management' version '1.1.7'
}

group = 'com.vodori.platform.ai'
version = '0.0.1-SNAPSHOT'

java {
    toolchain {
        languageVersion = JavaLanguageVersion.of(21)
    }
}

configurations {
    compileOnly {
        extendsFrom annotationProcessor
    }
}

repositories {
    mavenCentral()
}

ext {
    set('springAiVersion', "1.0.0-M8")
    set('testcontainersVersion', "1.21.0")
}

dependencies {

    //Spring Boot
    implementation 'org.springframework.boot:spring-boot-starter-security'
    implementation 'org.springframework.boot:spring-boot-starter-web'
    implementation 'org.springframework.boot:spring-boot-starter-webflux'
    implementation 'org.springframework.boot:spring-boot-starter-data-neo4j'
    implementation 'org.springframework.boot:spring-boot-starter-graphql'

    // Spring AI
    implementation 'org.springframework.ai:spring-ai-starter-model-openai'
    implementation 'org.springframework.ai:spring-ai-starter-vector-store-neo4j'

    //Spring AI MCP
    implementation 'org.springframework.ai:spring-ai-starter-mcp-client-webflux'
    implementation 'org.springframework.ai:spring-ai-starter-mcp-server-webflux'
    implementation 'org.springframework.ai:spring-ai-starter-mcp-client'
    implementation 'org.springframework.ai:spring-ai-starter-mcp-server'

    //Spring AI Document Readers
    implementation 'org.springframework.ai:spring-ai-tika-document-reader'
    implementation 'org.springframework.ai:spring-ai-pdf-document-reader'
    implementation 'org.springframework.ai:spring-ai-markdown-document-reader'


    compileOnly 'org.projectlombok:lombok'
    developmentOnly 'org.springframework.boot:spring-boot-devtools'
    annotationProcessor 'org.projectlombok:lombok'

    //Tests
    testImplementation 'org.springframework.boot:spring-boot-starter-test'
    testImplementation 'org.springframework.security:spring-security-test'
    testImplementation("org.wiremock:wiremock-standalone:3.4.2")
    testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
    testImplementation "org.testcontainers:junit-jupiter:${testcontainersVersion}"
    testImplementation "org.testcontainers:neo4j:${testcontainersVersion}"

}

dependencyManagement {
    imports {
        mavenBom "org.springframework.ai:spring-ai-bom:${springAiVersion}"
    }
}

tasks.named('test') {
    useJUnitPlatform()
}