I run a small Modded with some friends of mine. I updated Malum today (4-25-2022), however when I tried to run the server through the hosting site, Malum would present a datapack failure message. I tried downgrading but was met with the same message. Malum loads fine client side, and removing Malum fixed the issue.

The server log produced this:
To note, the Forge version of the server is 39.0.88

[20:31:41] [main/WARN]: Failed to load datapacks, can't proceed with server load. You can either fix your datapacks or reset to vanilla with --safeMode java.util.concurrent.ExecutionException: java.lang.NullPointerException: Cannot invoke "com.google.gson.JsonElement.getAsString()" because the return value of "com.google.gson.JsonObject.get(String)" is null at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:396) ~[?:?] at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:2073) ~[?:?] at net.minecraft.server.Main.main(Main.java:160) ~[server-1.18.1-20211210.034407-srg.jar%23151!/:?] at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?] at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) ~[?:?] at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?] at java.lang.reflect.Method.invoke(Method.java:568) ~[?:?] at net.minecraftforge.fml.loading.targets.CommonServerLaunchHandler.lambda$launchService$0(CommonServerLaunchHandler.java:46) ~[fmlloader-1.18.1-39.0.88.jar%2323!/:?] at cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:37) [modlauncher-9.1.0.jar%235!/:?] at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:53) [modlauncher-9.1.0.jar%235!/:?] at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:71) [modlauncher-9.1.0.jar%235!/:?] at cpw.mods.modlauncher.Launcher.run(Launcher.java:106) [modlauncher-9.1.0.jar%235!/:?] at cpw.mods.modlauncher.Launcher.main(Launcher.java:77) [modlauncher-9.1.0.jar%235!/:?] at cpw.mods.modlauncher.BootstrapLaunchConsumer.accept(BootstrapLaunchConsumer.java:26) [modlauncher-9.1.0.jar%235!/:?] at cpw.mods.modlauncher.BootstrapLaunchConsumer.accept(BootstrapLaunchConsumer.java:23) [modlauncher-9.1.0.jar%235!/:?] at cpw.mods.bootstraplauncher.BootstrapLauncher.main(BootstrapLauncher.java:149) [bootstraplauncher-1.0.0.jar:?] Caused by: java.lang.NullPointerException: Cannot invoke "com.google.gson.JsonElement.getAsString()" because the return value of "com.google.gson.JsonObject.get(String)" is null at com.sammy.malum.core.systems.recipe.SpiritWithCount.deserialize(SpiritWithCount.java:35) ~[malum-1.18.1-1.3.2.jar%23115!/:1.18.1-1.3.2] at com.sammy.malum.common.recipe.SpiritRepairRecipe$Serializer.fromJson(SpiritRepairRecipe.java:204) ~[malum-1.18.1-1.3.2.jar%23115!/:1.18.1-1.3.2] at com.sammy.malum.common.recipe.SpiritRepairRecipe$Serializer.m_6729_(SpiritRepairRecipe.java:154) ~[malum-1.18.1-1.3.2.jar%23115!/:1.18.1-1.3.2] at net.minecraft.world.item.crafting.RecipeManager.m_44045_(RecipeManager.java:144) ~[server-1.18.1-20211210.034407-srg.jar%23151!/:?] at net.minecraft.world.item.crafting.RecipeManager.m_5787_(RecipeManager.java:60) ~[server-1.18.1-20211210.034407-srg.jar%23151!/:?] at net.minecraft.world.item.crafting.RecipeManager.m_5787_(RecipeManager.java:35) ~[server-1.18.1-20211210.034407-srg.jar%23151!/:?] at net.minecraft.server.packs.resources.SimplePreparableReloadListener.m_10789_(SimplePreparableReloadListener.java:13) ~[server-1.18.1-20211210.034407-srg.jar%23151!/:?] at java.util.concurrent.CompletableFuture$UniAccept.tryFire(CompletableFuture.java:718) ~[?:?] at java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:482) ~[?:?] at net.minecraft.server.packs.resources.SimpleReloadInstance.m_143940_(SimpleReloadInstance.java:71) ~[server-1.18.1-20211210.034407-srg.jar%23151!/:?] at net.minecraft.server.packs.resources.SimpleReloadInstance.m_10834_(SimpleReloadInstance.java:70) ~[server-1.18.1-20211210.034407-srg.jar%23151!/:?] at java.util.concurrent.CompletableFuture$UniCompletion.claim(CompletableFuture.java:572) ~[?:?] at java.util.concurrent.CompletableFuture$UniAccept.tryFire(CompletableFuture.java:714) ~[?:?] at java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510) ~[?:?] at java.util.concurrent.CompletableFuture.postFire(CompletableFuture.java:614) ~[?:?] at java.util.concurrent.CompletableFuture$UniAccept.tryFire(CompletableFuture.java:726) ~[?:?] at java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:482) ~[?:?] at net.minecraft.server.packs.resources.SimpleReloadInstance.m_143940_(SimpleReloadInstance.java:71) ~[server-1.18.1-20211210.034407-srg.jar%23151!/:?] at net.minecraft.server.packs.resources.SimpleReloadInstance.m_10834_(SimpleReloadInstance.java:70) ~[server-1.18.1-20211210.034407-srg.jar%23151!/:?] at java.util.concurrent.CompletableFuture$UniCompletion.claim(CompletableFuture.java:572) ~[?:?] at java.util.concurrent.CompletableFuture$UniAccept.tryFire(CompletableFuture.java:714) ~[?:?] at java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510) ~[?:?] at java.util.concurrent.CompletableFuture.postFire(CompletableFuture.java:614) ~[?:?] at java.util.concurrent.CompletableFuture$UniAccept.tryFire(CompletableFuture.java:726) ~[?:?] at java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:482) ~[?:?] at net.minecraft.server.packs.resources.SimpleReloadInstance.m_143940_(SimpleReloadInstance.java:71) ~[server-1.18.1-20211210.034407-srg.jar%23151!/:?] at net.minecraft.server.packs.resources.SimpleReloadInstance.m_10834_(SimpleReloadInstance.java:70) ~[server-1.18.1-20211210.034407-srg.jar%23151!/:?] at java.util.concurrent.CompletableFuture$UniCompletion.claim(CompletableFuture.java:572) ~[?:?] at java.util.concurrent.CompletableFuture$UniAccept.tryFire(CompletableFuture.java:714) ~[?:?] at java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510) ~[?:?] at java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:2147) ~[?:?] at net.minecraft.server.packs.resources.SimpleReloadInstance$1.m_10855_(SimpleReloadInstance.java:53) ~[server-1.18.1-20211210.034407-srg.jar%23151!/:?] at net.minecraft.server.packs.resources.SimpleReloadInstance$1.m_6769_(SimpleReloadInstance.java:50) ~[server-1.18.1-20211210.034407-srg.jar%23151!/:?] at java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1150) ~[?:?] at java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510) ~[?:?] at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1773) ~[?:?] at java.util.concurrent.CompletableFuture$AsyncSupply.exec(CompletableFuture.java:1760) ~[?:?] at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:373) ~[?:?] at java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1182) ~[?:?] at java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1655) ~[?:?] at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1622) ~[?:?] at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:165) ~[?:?]

It appears that my github webhook, which links me to newly-posted github issues has somehow skipped a few, including this one. I believe this should be fixed in newer releases.