1, the parties to the main contract collude to defraud the guarantor to provide a guarantee, or the creditors of the main contract resort to fraud, coercion and other means to make the guarantor provide a guarantee against the true meaning;

2, beyond the warranty period;

3. Changing the main contract without the consent of the guarantor;

4. Transferring debts without the consent of the guarantor;

5. The main contract is invalid.

Can the guarantor entrust others to sign?

The guarantor may entrust others to sign, but must provide a power of attorney. The guarantor cannot sign for various reasons. If the real guarantor knows that you are signing for him, let him issue a power of attorney. Forging the signature of the guarantor, the validity of the guarantee contract is to be determined, and it will not have legal effect on the guarantor without ratification by the guarantor. If so, it may be suspected of loan fraud. In addition, from a civil point of view, it means that there is no actual guarantor. Forged signatures and fingerprints belong to forged evidence, and legal responsibilities can be investigated according to the purpose and circumstances of forged evidence.

Legal basis: Article 388 of the Civil Code of People's Republic of China (PRC).

To establish a security interest, a security contract shall be concluded in accordance with the provisions of this Law and other laws. Guarantee contracts include mortgage contracts, pledge contracts and other contracts with guarantee functions. The guarantee contract is a subsidiary contract of the main creditor's rights and debts contract. If the principal creditor's rights and debts contract is invalid, the guarantee contract is invalid, unless otherwise stipulated by law. If the debtor, guarantor and creditor are at fault after the guaranty contract is confirmed to be invalid, they shall bear corresponding civil liabilities according to their faults.