Sync will appear Failed, but cannot reach 100%, what is the general reason?

Sync will appear Failed, but cannot reach 100%, what is the general reason?
In addition, what is the best way for me to write, deploy, upgrade, and test subgraphs?

Now For Me:

  1. graph cli + abi → init a project (Rinkeby)
  2. write mapping and schema ,then. codegen and build
  3. Token auth and Deploy to upload IPFS and The Graph
  4. see on the graph playground

but when I got a error or fail , I need wait sync and then to fix it ?

is there the better way for this ?