There is always the risk of default. However, depending on the type of bond, this may not be likely to happen. Aside from default, there are also other risks to consider.
Sovereign risks apply to government bonds. Although government bonds are low-risk, the government can still change its policies on how it repays its debts, which will affect the interest you earn.
There is a chance that after you buy bonds, your issuer may offer new bonds with a higher interest rate than the ones you bought. This is an interest rate risk, and if you were to keep the bond you bought, you could miss out on higher potential earnings.
Your bond’s market value can also be affected by changes in interest rates – if your bond’s interest rate is considered lower than the bonds that your issuer is currently offering, it can be harder to sell your bond.
There is also a call and prepayment risk for most bonds, where your bond issuer may decide to return your principal early, so you will not be able to enjoy interest payments until the maturity date.
Not all risks would come from the bond issuer. When you buy bonds, you put aside a large amount of cash for a long time. Although you would get your principal back at the maturity date, there is a chance that you may need that cash for emergencies before your bond matures. If this happens, there is the risk of not being able to sell your bond, missing out on future interest payments, or having to sell your bond at a lower price.
Also, since bonds are mostly sold over-the-counter, it can be difficult to determine what a good price is, so there is a risk that you may be charged higher than what is fair.