"Unable to find all tx inputs" I've created a transaction using "bitcoinjs-lib".

Here is the hash:

01000000013f3e32e0b436f37d6c67265dd0cb71053fe6b6f9cee12efbe52065071215d37b000000006a47304402203dc1f1d173ac8eaa059ef6f703793d16c98a33f1d6e2b6b83b894517041fdc08022065e57c6ad4c3f371348334b6aa27188ce4719f6278dc18003f60d4081b423c2401210273abe13a1fefd8663f7deeb4e755ad8753481fc6204b24e244835207edcbb760ffffffff02e8030000000000001976a91414c50581bac21c1fa611f906db135736d87e4c5088ac54820100000000001976a91463978c3bc763ceb4981d6992224d4b0c2892652888ac00000000


Here is the value of this hash.

{
   "lock_time":0,
   "size":225,
   "inputs":[
      {
         "prev_out":{
            "index":0,
            "hash":"7bd31512076520e5fb2ee1cef9b6e63f0571cbd05d26676c7df336b4e0323e3f"
         },
         "script":"47304402203dc1f1d173ac8eaa059ef6f703793d16c98a33f1d6e2b6b83b894517041fdc08022065e57c6ad4c3f371348334b6aa27188ce4719f6278dc18003f60d4081b423c2401210273abe13a1fefd8663f7deeb4e755ad8753481fc6204b24e244835207edcbb760"
      }
   ],
   "version":1,
   "vin_sz":1,
   "hash":"a85b07d647f728986687933f30db758b545144b34e9110d78355b2c11efc8423",
   "vout_sz":2,
   "out":[
      {
         "script_string":"OP_DUP OP_HASH160 14c50581bac21c1fa611f906db135736d87e4c50 OP_EQUALVERIFY OP_CHECKSIG",
         "address":"12tpY8cF2bfTUzTQSZjwhRZ2k33RGNKzpg",
         "value":1000,
         "script":"76a91414c50581bac21c1fa611f906db135736d87e4c5088ac"
      },
      {
         "script_string":"OP_DUP OP_HASH160 63978c3bc763ceb4981d6992224d4b0c28926528 OP_EQUALVERIFY OP_CHECKSIG",
         "address":"1A5bSiXqBBt4rSani8UHaAV4314pU8poN9",
         "value":98900,
         "script":"76a91463978c3bc763ceb4981d6992224d4b0c2892652888ac"
      }
   ]
}


Blockchain gives the error "Unable to find all tx inputs".

Why is this (and how do I fix it)?
If I'm reading correctly, your input transaction is  7bd31512076520e5fb2ee1cef9b6e63f0571cbd05d26676c7df336b4e0323e3f.  This transaction is not found by a search on blockchain.info.  I would guess one of the following is true:


The transaction id is incorrect
The transaction was never broadcast
The transaction was broadcast, but was never confirmed, and so much time has passed that  blockchain.info stopped keeping track of it.


So, check that the id is correct, and if it is, try (re)broadcasting the transaction.