facebook/fresco

Fatal Exception: java.lang.NullPointerException: Attempt to get length of null array

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#2,504 opened on May 26, 2020

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Description

We are getting following crash on Crashlytics for good number of users with Android OS 8, with more than 47 devices. We are using "com.facebook.fresco:fresco:2.2.0"

Could you please help us, since its happening on. multiple users.

Logs :

Fatal Exception: java.lang.NullPointerException: Attempt to get length of null array at java.util.Formatter$FormatSpecifier.addZeros(Formatter.java:3505) at java.util.Formatter$FormatSpecifier.print(Formatter.java:3401) at java.util.Formatter$FormatSpecifier.print(Formatter.java:3332) at java.util.Formatter$FormatSpecifier.print(Formatter.java:3317) at java.util.Formatter$FormatSpecifier.printFloat(Formatter.java:2891) at java.util.Formatter$FormatSpecifier.print(Formatter.java:2844) at java.util.Formatter.format(Formatter.java:2523) at java.util.Formatter.format(Formatter.java:2458) at java.lang.String.format(String.java:2814) at com.facebook.common.logging.FLog.formatString(FLog.java:491) at com.facebook.common.logging.FLog.v(FLog.java:118) at com.facebook.imagepipeline.transcoder.DownsampleUtil.determineDownsampleRatio(DownsampleUtil.java:87) at com.facebook.imagepipeline.transcoder.DownsampleUtil.determineSampleSize(DownsampleUtil.java:43) at com.facebook.imagepipeline.producers.DecodeProducer$ProgressiveDecoder$1.run(DecodeProducer.java:163) at com.facebook.imagepipeline.producers.JobScheduler.doJob(JobScheduler.java:202) at com.facebook.imagepipeline.producers.JobScheduler.access$000(JobScheduler.java:22) at com.facebook.imagepipeline.producers.JobScheduler$1.run(JobScheduler.java:73) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636) at com.facebook.imagepipeline.core.PriorityThreadFactory$1.run(PriorityThreadFactory.java:51) at java.lang.Thread.run(Thread.java:764)

Contributor guide

Tech stack
java
Domain
mobile
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
needs investigation
Prerequisites
basic JavaAndroid logging
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
The stack trace points to a NullPointerException in `java.util.Formatter$FormatSpecifier.addZeros` called from `FLog.formatString` at line 491. The crash occurs in `DownsampleUtil.determineDownsampleRatio` (line 87) and `DecodeProducer$ProgressiveDecoder$1.run` (line 163). Investigate the `FLog.formatString` method in the Fresco codebase to identify why a null array is passed to `String.format`. Check if there is a missing null check for the format arguments. Additionally, review the `DownsampleUtil` class to understand the context in which the logging is invoked. The issue is reproducible on Android 8 across many devices; consider testing with an emulator running API 26. Look at the existing comments in issue #2504 for any further hints from maintainers.