Java APNS Certificate Error with "DerInputStream.getLength(): lengthTag=109, too big."

This occurs because the system thinks you are trying to read a different type of keystore and not JKS. You will need to specify that the file is JKS or convert it to the other format.

I see that you have already tried converting to .p12. If you did this correctly, perhaps there is some other default format. I recommend finding out how to specify JKS instead.

I had the same problem but my solution will help you only if you are using maven.

Maven resource filtering (that let's you include variables in your resource files) can mess up your binaries - and certificates are especially sensitive to modification.

In general, binary content shouldn't be filtered. But I couldn't just simply disable resource filtering because I have some .properties files that include variables. So the solution was to exclude .p12 files from filtering.

<build>
    [...]
    <resources>
        <resource>
            <directory>src/main/resources</directory>
            <filtering>true</filtering>
            <excludes>
                <exclude>**/*.p12</exclude>
            </excludes>
        </resource>
        <resource>
            <directory>src/main/resources</directory>
            <filtering>false</filtering>
            <includes>
                <include>**/*.p12</include>
            </includes>
        </resource>
    </resources>
    [...]
</build>

More about maven resource filtering: http://maven.apache.org/plugins/maven-resources-plugin/examples/filter.html

If you use maven, this is probably occurring because of the Maven filtering in your whole resources folder. I've tried Zsolt Safrany solution above and did not work. However, reading the documentation he shared, I've found this:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-resources-plugin</artifactId>
  <version>3.0.1</version>
  <configuration>
    <nonFilteredFileExtensions>
      <nonFilteredFileExtension>p12</nonFilteredFileExtension>
    </nonFilteredFileExtensions>
  </configuration>
</plugin>

Which excludes binary extensions (or any extension you want) from being filtered.