Can Somebody help me stop my geckolib entity from crashing Minecraft

 Is the animation's name is same with model's name?

it should be etc.   name.geo.json/name.animation.json

You may have entered some parameters incorrectly. Personally, instead of using geckolib, I make a mob by coding the java model, which is more stable and proportional, compatible with the animation.
Frankly, geckolib is not a good plugin at all. and makes your mod dependent on another mod. I don't want my mod to be dependent on another mod. That's why I don't use geckolib and I solve it by coding. All this aside, it only allows linear animation. I can't use smooth animation keyframe. But the worst part is that when we want to play a special animation in the mob we made, it is only compatible with certain triggers. So we cannot use all the trigger events we want. For example, I want an animation to play when lightning strikes the mob we made. but geckolib is not compatible with this trigger. This is just an example. Finally, I would like to add this: the java model with only arm, leg and head animation is better than geckolib. Because we enter walking speed and attack speed in the behavior parameters of the mob we make, and mcreator proportions the animations of the java model with the parameters we enter. But geckolib is not like that. I went crazy until I managed to match the walking speed in the animation we made in mcreator.

As for your problem: geckolib entity model is in ".json" file format. animation is also in this format. so put ".geo" before ".json" in the name of the model file. (example.geo.json) is not much different in the case of animation: put ".animation" before ".json". (example.animation.json) I was getting this error frequently when I was using geckolib. Double-check the names you entered. If you are using minecraft 1.18 and above, just write the name you gave in blockbench in the animation definition section of the mob you made. You just need to write the name. You do not need to write the ".animation.json" part after the animation name. If you are using an older version of mcreator or a generator that allows you to make mods between 1.18-1.16, create a new forum, I will most likely give feedback. Before closing the subject, let me tell you a possible reason: the model you designed may have been degraded. In this case, if you saved your model as a blockbench project (.bbmodel), open it and there is a "file" text at the top of the application. When you hover the mouse cursor over that text, a box will open. Click "convert project" in that box. On the screen that appears, select the model type as "geckolib animated model". After checking the "make copy" checkbox, a converted copy of the same model will be opened. Likewise, find the word "file" in the toolbar at the top of the application. Select export in the box that appears and export your model as a geckolib model. It would be useful to review the animations as well.

Are you using original minecraft launcher?

Is the name of the mod test3?

There are all kinds of bug-fix variations in the world of software and coding, including modding Minecraft. It can take years to find the right one.

https://drive.google.com/drive/folders/1tscukUCR6dqjht9dfoyMv4R3N6RkJNfg?usp=sharing

Are you sure you chose the right forge version? For example, forge versions for minecraft 1.16.5 are from 36.1.0 to 36.2.39. I think you are using 1.19. Forge versions for 1.19 are from 41.1.0 to 45.1.19. There is a folder in the link above and there are 2 pictures in it, you can learn the forge version of the mod by looking at them.

Most importantly, I would like to point out this: The animations you make in blockbench should not overlap. What I mean is that when adding a linear or smooth type of animation step to a group of parts, they should not overlap each other even half the time. this causes a crash. Additionally, if the mob you design takes up space close to, equal to or more than 1 chunk, this will also cause a crash. In order for each chunk to be optimized in Minecraft's code, if there are entities in the chunk, the number of these entities must be at least 3. However, if you have made a very large mob and it covers the entire chunk on its own, if it contains too many parts, if it has too many and complex animations, it will either crash the game or lag forever in that world. Such lags have microsecond gaps. Since we do not know when this gap will occur, you must enter the "/kill @e" command and press enter just before it occurs. When the gap moment occurs, the lag will be resolved and the command will run automatically. If there are unnecessary parts that you forgot to remove while making the design, review them. It is also useful to group all parts together with parts of the same type as much as possible. This reduces subsidence.